Simple repack on CI

Usage: cta-admin --json <command> <subcommand> <options>

For stream commands only (where each line of the result is sent back in
a protocol buffer), return the results in JSON format instead of a
text table.

Better to have all formatting on the client side, so we format the
header and the reponse values in the same place. (Also no need to
send this data over the wire as it's always the same).

OptionStrList takes a filename as its value. It reads the file into a
list of strings in the protobuf. On the server side, the values are
unpacked and made available as std::vector<std::string>.

For example implementation, see "cta-admin repack add"

Default now set to 10s. Note that XRD_TIMEOUTRESOLUTION must be set
<= 10s, otherwise timeout defaults to 15s.

This allows specifying different protocol buffers for EOS and CTA Admin
messages, both of which must be processed by the same XRootD plugin in
the CTA Frontend.

Use precision .00 for Mbytes. Move library name to the front.

Converted all bytes to Mbytes. Removed extra space in the output.
Reordered fields.

First version of a streaming "cta archivefile ls" command.

Fixed the timings so they show up in all states.
Removed lds command.
Added error message when a drive is not found for single drive ls.

Removed the member variable XrdCtaFile::error that was incorrectly
shadowing XrdSfsFile::error.

Added the XrdCtaFile::m_listingArchiveFiles member variable and
factorized XrdCtaFile::readFromCmdlineOutput() out from
XrdCtaFile::read() so that in the future the XrdCtaFile::read()
method will be able to treat the listing of archive files
differently from other cta commands.

Currently none of the cta commands are incrementally generating
and streaming large result sets back to the cta command-line
tool.  All commands are generating the entire result in the
constructor of XrdCtaFile.  The result is streamed back to the
cta command-line tool, but the result is generated in one
single stepi before any streaming starts.

The listing of archive files is being gradually modified to
incrementaly generate the result in each call to
XrdCtaFile::read().  This commit is one step in this
larger modification.

Removed unnecessary member variable XrdCtaFile::m_cmdlineReturnCode