Resolve "TABLE TEMP_DISK_FXIDS is missing in the schema but is defined in the catalogue database when cta-restore-deleted-files is run with postgreSQL"

Restoring deleted files implies restoring them in the eos namespace and
in the cta catalogue. The command has no atomicity guarantees, a file
may be restored in the eos namespace but the restoring in the cta
catalogue may fail.

Made the dotted line surrounding the wrapper::rdbms classes within cta_rdbms_class_diagram.svg more visible

Improved human readability by correcting the order of the ORA error codes in OcciStmt::connShouldBeClosed()

This reverts commit 18b07b1f.

[catalogue] Fixed #845 An RdbmsCatalogue iterator should return its underlying database connection when the last row has been fetched

cta-catalogue-schema-verify tool

Added --build and --drop to the cta-statistics-save so that we can create and drop the tables needed for the statistics