Add a configuration option to execute commands on startup.

[mlefebvre]

Description

Related issue: #247

I needed a way to execute commands on startup (like SET default_transaction_read_only = on when connecting on a production server), so I added a new startup_command configuration option.

Checklist

• [x] I've added this contribution to the changelog.rst.
• [x I've added my name to the AUTHORS file (or it's already there).
• [x] I installed pre-commit hooks (pip install pre-commit && pre-commit install), and ran black on my code.
• [x] Please squash merge this pull request (uncheck if you'd like us to merge as multiple commits)

[codecov-commenter]

Codecov Report

Base: 84.15% // Head: 79.40% // Decreases project coverage by -4.74% :warning:

Coverage data is based on head (31879f9) compared to base (6884c29). Patch coverage: 42.20% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1294      +/-   ##
==========================================
- Coverage   84.15%   79.40%   -4.75%     
==========================================
  Files          21       24       +3     
  Lines        2720     2904     +184     
==========================================
+ Hits         2289     2306      +17     
- Misses        431      598     +167     

Impacted Files	Coverage Δ
pgcli/packages/parseutils/tables.py	97.67% <ø> (ø)
pgcli/packages/sqlcompletion.py	97.67% <ø> (ø)
pgcli/pgtoolbar.py	31.57% <0.00%> (+0.15%)	:arrow_up:
pgcli/pyev.py	15.38% <15.38%> (ø)
pgcli/explain_output_formatter.py	46.15% <46.15%> (ø)
pgcli/key_bindings.py	52.94% <50.00%> (-0.19%)	:arrow_down:
pgcli/main.py	78.44% <86.66%> (-0.09%)	:arrow_down:
pgcli/pgexecute.py	83.22% <87.14%> (+2.86%)	:arrow_up:
pgcli/auth.py	91.30% <91.30%> (ø)
pgcli/__init__.py	100.00% <100.00%> (ø)
... and 6 more

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[j-bennet]

Hey @mlefebvre, do you need some help with this PR? This seems like a useful feature, would be nice to get it in.

[j-bennet]

Hi @mlefebvre, I tested your PR, things work fine. If you rebase on main, I'll merge this without a test.

[mlefebvre]

Sorry @j-bennet , I had completely forgotten about this!

We found a different way to achieve what we wanted to do, so we didn't need the feature anymore.

[j-bennet]

@mlefebvre

Thank you for getting back to me. If you don't intend to continue working on it, I'll close the PR.

Can you share how you solved this, so other users can benefit from your solution?