feat: WER integration

[jpnurmi]

Based on:

• feat(internal): add scope observer #1839
• feat(internal): add clean SDK integration points #1848

The WER (Windows Error Reporting) integration:

• enabled via cmake -DSENTRY_INTEGRATION_WER=ON (inspired by the existing Qt integration)
• automatically wired up during sentry_init
• based on the scope observer API (sentry_scope_observer_t, also WIP)
• syncs tags and attachments to WER
  • WerRegisterCustomMetadata / WerUnregisterCustomMetadata (Windows 10 1703+)
  • WerRegisterFile / WerUnregisterFile
  • WerRegisterMemoryBlock / WerUnregisterMemoryBlock

The implementation is backend-agnostic, but does not work with breakpad or crashpad, which prevent WER from handling exceptions.

> pytest -v --with_wer tests\test_integration_wer.py
=================================================================== test session starts ====================================================================
platform win32 -- Python 3.13.3, pytest-9.0.3, pluggy-1.6.0 -- C:\Users\jpnurmi\Projects\sentry\sentry-native\.venv\Scripts\python.exe
cachedir: .pytest_cache
rootdir: C:\Users\jpnurmi\Projects\sentry\sentry-native
plugins: flaky-3.8.1, pytest_httpserver-1.0.10, xdist-3.8.0
collected 5 items

tests/test_integration_wer.py::test_wer_custom_metadata[none] PASSED                                                                                  [ 20%]
tests/test_integration_wer.py::test_wer_custom_metadata[inproc] PASSED                                                                                [ 40%]
tests/test_integration_wer.py::test_wer_custom_metadata[breakpad] XFAIL (breakpad swallows the exception)                                             [ 60%]
tests/test_integration_wer.py::test_wer_custom_metadata[crashpad] XFAIL (crashpad handler terminates the process)                                     [ 80%]
tests/test_integration_wer.py::test_wer_custom_metadata[native] PASSED                                                                                [100%]

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.76%. Comparing base (cb14a09) to head (9a2b042).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1837   +/-   ##
=======================================
  Coverage   75.76%   75.76%           
=======================================
  Files          92       92           
  Lines       21989    21989           
  Branches     3918     3918           
=======================================
+ Hits        16660    16661    +1     
  Misses       4447     4447           
+ Partials      882      881    -1     

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[github-actions]

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