FTS-1835: Look for custom "audience" and "requested_token_type" options in the token exchange workflow

FTS-1857: Introduce "archive_metadata" file property

Closes FTS-1857

See merge request !91

FTS-1858: Do not attempt certificate delegation when no certificate is loaded. This will avoid a Python Type error

This commit introduces the following changes:
  - Introduces "--archive-metadata" as a new parameter for file transfers"
  - Stores the submitted "archive_metadata" per file in the "t_file" table
  - Sends the "archive_metadata" in the "state_change" monit messages

Document "--copy-pin-lifetime" and "--bring-online" options to make clear that these options will create a bring online operation in FTS

FTS-1815: Implement the "/admin/force-start" endpoint to allow administrators to kickstart transfers

This change also required the introduction of a new "admin" authorization level.
The "/admin/force-start" endpoint requires the "admin" level.

- fts3-el7 / dmc-el7: production repository
- fts3-rc-el7 / dmc-rc-el7: release candidates repository
- fts3-devel-el7 / dmc-devel-el7: continuously built from the development branch

CI: Install the "fts-depend" repository in the "rpm-tests" job. Previously, these packages were fetched from the "fts-testing" repository

The introduction of a new "FORCE_START" file state broke the previous assumption that the file state will be the same as the job state

Added endpoint PUT /jobs/<job_id>/files/<comma,sep,file,ids> to FORCE_START files which are SUBMITTED

FTS-1575: Loop over the certificate chain and take the minimum "lifetime" as the delegated proxy expiration time

  - The json.dumps(..) function returns the string "null" if the provided argument is of type None
  - Before calling json.dumps(..) we should check if the argument is of type None to avoid storing the string "null" in the database when nothing should be stored

Profile jobs

See merge request !90