feat: add linux distributions to os context

[supervacuus]

Fixes #943.

This adds Linux distribution meta-data to the os context as follows:

Only name and version should be indexed.

Further steps required before we merge/release this:

• update event payload docs for OS context: feat: add Linux distributions to the os context develop#1227
• add definitions in relay: feat(protocol): Add Linux distributions to os context relay#3443
• add indexing support for name and version: Make os.distribution searchable sentry#69865
• restructure event-payload to be flat (i.e. distribution_name instead of distribution.name, etc.)
• apply flat structure to develop-docs (+ fix the link in develop-docs back to a commit in master: fix: 404 links in develop-docs sentry-docs#10768)
• apply flat structure to relay
• apply flat structure to indexing support

[github-actions]

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Generated by 🚫 dangerJS against 1699009

[codecov]

Codecov Report

Attention: Patch coverage is 90.47619% with 10 lines in your changes missing coverage. Please review.

Project coverage is 82.55%. Comparing base (235f837) to head (1699009).
Report is 64 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #963      +/-   ##
==========================================
- Coverage   86.53%   82.55%   -3.98%     
==========================================
  Files          40       53      +13     
  Lines        3736     7860    +4124     
  Branches        0     1232    +1232     
==========================================
+ Hits         3233     6489    +3256     
- Misses        503     1260     +757     
- Partials        0      111     +111     

[supervacuus]

The failing Mingw test is unrelated to the change (a change in the GHA runner image requires us to install zlib for MinGW).

[supervacuus]

@markushi, @Swatinem, can one of you give this a thorough look?

[markushi]

Left a few minor nits, looking good!

[supervacuus]

again, failing test here is due to: #968

[supervacuus]

PR is on hold until the context format is clarified. Nested context formats with three layers are unacceptable for the backend to search, so we either change the format in the SDK or map it locally in the sentry backend.

Since the format was at the core of how to add this feature from the start, it is best to change the format in the SDK (and with it, in the develop-docs, relay, and sentry backend).

This is currently deprioritized.