Specify server timeout

[just-an-engineer]

This should fix issue #2237, where in the case a compilation is still ongoing when a shutdown request is sent, and it's a larger/complex codebase that takes longer than the default 10 seconds, the user can now specify it in their config file.

However, I'd like to also propose a breaking change for config files, moving server_startup_timeout_ms and server_shutdown_timeout_ms to a specific timing struct. I left the code in there to do this, just commented out. I'd like to make this change next time we bump up a major version.
Although I can remove the comments to clean up the code until then. But what's the best practice for marking a milestone? Should I raise an issue?

[just-an-engineer]

If a breaking change will occur in 0.9, like @Xuanwo had mentioned in PR #2235, talking about the issue to replace rouille with axum, then I can go ahead and change this PR to include that breaking change for the config file, and we can merge this in with 0.9. If that will occur. Otherwise, it's ready to go, outside of the comment I previously wrote

[sylvestre]

seems that rustfmt needs to be run
also, could you please document this into the readme file? thanks

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 50.00000% with 24 lines in your changes missing coverage. Please review.

Project coverage is 51.67%. Comparing base (0cc0c62) to head (554425c).
Report is 72 commits behind head on main.

Files with missing lines	Patch %	Lines
src/config.rs	52.50%	2 Missing and 17 partials ⚠️
src/server.rs	0.00%	0 Missing and 3 partials ⚠️
tests/oauth.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2246       +/-   ##
===========================================
+ Coverage   30.91%   51.67%   +20.76%     
===========================================
  Files          53       54        +1     
  Lines       20112    20751      +639     
  Branches     9755     9795       +40     
===========================================
+ Hits         6217    10724     +4507     
- Misses       7922     8026      +104     
+ Partials     5973     2001     -3972     

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