ADBM-2913: Implement repo-push command

[dkovalev1]

Our users need the ability to quickly restore tables (or sets of tables) from
a backup without the need to restore whole database. This accelerates recovery
operations after incidents such as accidenatal deletion/corruption of data and
saves disk space and time.

To support it the repo-push command is designed to manage metadata files in
the pgBackRest repository. This command allows saving table metadata associated
with restore points. The metadata is stored in the same repository as
the restore points and inherits the compression settings from the main
pgBackRest configuration file.

This commit implements repo-push command.

ADBM-2913

[bandetto]

Do I understand correctly, the purpose of repo-push is to push arbitrary files, which are called 'metadata' to the repository?

In the spec metadata files presented as JSON. Are files validated to be JSON anywhere?

[dkovalev1]

Do I understand correctly, the purpose of repo-push is to push arbitrary files, which are called 'metadata' to the repository?

yes, that's right.

In the spec metadata files presented as JSON. Are files validated to be JSON anywhere?

No, pgbackrest do not care of the files content. They are going to be used for a metadata files, but from pgbackrest side it can be any files.

[bandetto]

They are going to be used for a metadata files, but from pgbackrest side it can be any files.

Ok, if that case was discussed with the architect.

[bandetto]

LGTM. Are tests ok?