[DPE-5484] Add TLS flag + CA to relation databag

[lucasgameiroborges]

Issue

#698, #732

Solution

Set TLS flag inside the databag, using the existing interface. If TLS is set, then tls_ca is populated. See corresponding PR on relation-interfaces repo here: canonical/charm-relation-interfaces#185

Tested locally the way CS expected it to work (based on this un-merged PR commit: canonical/temporal-k8s-operator@a7e50f0) and confirmed it works as excepted (ie event.tls returns either True or False).

[codecov]

Codecov Report

Attention: Patch coverage is 57.14286% with 6 lines in your changes missing coverage. Please review.

Project coverage is 71.67%. Comparing base (2a53fa3) to head (c88430f).
Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
src/relations/postgresql_provider.py	50.00%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #719      +/-   ##
==========================================
+ Coverage   71.65%   71.67%   +0.01%     
==========================================
  Files          11       12       +1     
  Lines        3031     3061      +30     
  Branches      464      468       +4     
==========================================
+ Hits         2172     2194      +22     
- Misses        753      758       +5     
- Partials      106      109       +3     

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[marceloneppel]

LGTM!