Ported commits from castor/master for Encryption:

6b6374d6c2e209c98c0d4d7aa665e1df83d71aaa
  CASTOR-5350: Introduce encryption SCSI commands in tape drive
  backend

  Implementation of two methods:
    * setEncryptionKey(key): Sets encryption params to drive.
    * clearEncryptionKey: Clears encryption params from drive.

3cf91d48f5c7b0cb563c3037aee69ec769f5ab94
  Added support for an interface script that will setup drive
  encryption per tape

e9ca601687508de20fab7154e63bb0dbd1b25a8a
  Migrate TapeWriteSingleThread::TapeCleaning::~TapeCleaning() body to
  .cpp

266b02d8175b5cfc0b688135cbdc335e93060b
  CASTOR-5350: Refactor support for only external key management script

789b26a0bc69053ff1ab792a02676a7753f093ed
  Merge branch 'encryption_backend' into 'master'

  CASTOR-5350: Encryption backend

  ## Description
    The aim of this merge request is to incorporate encryption support
    into CASTOR.
    The proposed changes are to be used in conjunction with the
    operators'
    [ExternalEncryptionKeyScript](https://gitlab.cern.ch/slaskari/castor-get-encryption-key).

    The **aim** is to enable encryption in specific tape pools of
    CASTOR.
  ## Changes
    * Introduce encryption SCSI backend to DriveGeneric.
    * Introduce encryption control wrapper
    * (`castor/tape/tapeserver/daemon/EncryptionControl`) for
    * abstracting the two sub-components of:
      * Calling the `ExternalEncryptionKeyScript`,
      * Calling the equivalent DriveGeneric function for
      * passing/clearing the encryption parameters to/from the drive.
    * Add new configuration option in `castor.conf` for the external key
    * management script.
    * Create a Subprocess wrapper for executing external commands as
    * CASTOR children (`castor/server/Subprocess.{h,c}pp`).
    * Incorporate encryption handling in the:
      * DataTransferSession
      * LabelSession
      * CleanerSession
    * Add encryption control timer in the task Watchdog.
  See merge request !1

fa550707c42d80466bbd448e355aaf9be5ea8e04
  Clear encryption key only when encryption enabled
  Changes include:
    - Making EncryptionControl stateful
    - Calling clearEncryptionKey on the drive only when encryption is
      on.
  Also includes a minor duplicate code fix on DriveGeneric.
cf4eb9f3ae36c9cfc9c40349d69ab6642020e81e
  Merge branch 'encryption_changes' into 'master'
  Clear encryption key only when encryption enabled
  ## Description
    Changes include:
    - Making EncryptionControl stateful
    - Calling `clearEncryptionKey()` on the drive only when encryption
      is on.
    Also includes a minor duplicate code fix on **DriveGeneric.cpp**.
  See merge request !2

40366d963ee33ca081df6c991189b21369e461fd
  Check if the drive has encryption capability enabled:
    * Add isEncryptionCapEnabled() vendor-specific function
    * Check isEncryptionCapEnabled() before passing encryption params
    * Check isEncryptionCapEnabled() before clearing encryption params
    * Clear encryption key before unencrypted I/O

4ccc661d01eccfc3fdfb9ee2578d15a147a0c55a
  Merge branch 'encryption_capability_enabled' into 'master'
  Drive encryption capabilities inclusion
  ## Description
    The aim of this merge request is to address issues related to
    encryption on drive without the encryption capability enabled.
    More specifically:
      * It introduces a vendor-specific way of identifying if the drive
      * has encryption capability enabled
      * **IBM**: Through the SPIN index SCSI page
      * **Oracle**: Through the general INQUIRY SCSI page
      * If the data to be written are to be encrypted, an additional check
      * of the encryption capability of the drive is made. In case of
      * encrypted data, but no encryption capability, the session fails.
      In essence, all encryption related operations are made modulo the
    encryption capability of the drive.
      Last, in case of unencrypted I/O, we clear the keys of the drive (if
    encryption capable) to avoid encrypted data with previous keys on
    CASTOR's system failure.
  ## Testing
    Before the merge request's submission, the following tests were
    passed:
      On drives with **encryption capability enabled**:
        * Label session
        * Label with previously set encryption key
        * Write without encryption
        * Read without encryption
        * Write with encryption
        * Read with encryption
        * Write with previously set encryption key
        * Read with previously set encryption key
      On drive with **encryption cabability disabled**:
        * Label session
        * Write without encryption
        * Read without encryption
        * Write with encryption - session **should** fail
        * Read with encryption - session **should** fail
    See merge request !3

55b85a2cb4681d697565116c00ff98c6becea4fb
  Secure session against invalid encryption script output

3a54875c680fe6c1c9d5cf25cf98d2780196e0d1
  Changes in encryption workflow
    - VMGR tag is updated only on write operations
    - Empty key signifies no encryption

f5408cf0ccbae9a4ab94a533f3b6d7be323f72fb
  Minor encryption log enhancements
    * Error line in Read/Write session with ErrorMesage key
    * Fix for delimiter in the end of arguments in argsToString()
2e7204fb0dd24b472a959fa5e13320c34df4f017
  Merging in improvements on tape encryption support.

92533a1746d0744ee528781558a720c63ca3c4d1
  Removed nullptr which is not supported in SLC6's gcc.
  Added automatic deletion of json objects in
  EncryptionControl::parse_json_script_output.

fca3bb9e7fce364b429fc0b5c036fb752fd67ff1
  Fix log typo