Add workload version to juju status

[amandahla]

This PR adds the Synapse version to the workload version so the user can check using the juju status command.
The version can be obtained through a request to the API.

The workload version is set on config-change event for a particular reason: when the charm is deployed, waits for a server_name config. So the user must set by using "juju config synapse server_name=foo". There is a retry configuration because Synapse is restarted after the change.

What happens after merging it:

• Add docs to metadata
• Add alive check
• Add new method to get version
• Add unit and integration tests

[jdkandersson]

Generally speaking, raising an exception within a function and then handling it within the same function is confusing for the reader and indicates opportunities to improve the error handling flow in a function

[github-actions]

Test coverage for e7d0af5

Name                            Stmts   Miss Branch BrPart  Cover   Missing
---------------------------------------------------------------------------
src/actions/__init__.py             3      0      0      0   100%
src/actions/register_user.py       20      0      2      0   100%
src/actions/reset_instance.py      21      3      2      1    83%   54-58
src/charm.py                       96      4     10      1    95%   92-93, 154-155
src/charm_state.py                 45      2     10      2    93%   22, 79
src/charm_types.py                  8      0      0      0   100%
src/constants.py                   12      0      0      0   100%
src/database_client.py             53      1     10      3    94%   35, 47->exit, 69->exit
src/database_observer.py           54      4      6      0    93%   70-72, 96
src/exceptions.py                   4      0      0      0   100%
src/observability.py                9      0      0      0   100%
src/pebble.py                      47      0      0      0   100%
src/synapse/__init__.py             3      0      0      0   100%
src/synapse/api.py                 83      2     10      1    97%   138-139
src/synapse/workload.py            94      3     10      1    96%   161, 292-297
src/user.py                        23      0      4      0   100%
---------------------------------------------------------------------------
TOTAL                             575     19     64      9    96%

Static code analysis report

Run started:2023-08-17 13:45:28.490131

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 2590
  Total lines skipped (#nosec): 1
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):