feat: Update Crashpad and enable Linux support

[Swatinem]

supersedes #307

[codecov-commenter]

Codecov Report

Merging #320 into master will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #320      +/-   ##
==========================================
- Coverage   85.21%   85.20%   -0.01%     
==========================================
  Files          49       49              
  Lines        3963     3961       -2     
==========================================
- Hits         3377     3375       -2     
  Misses        586      586              

Impacted Files	Coverage Δ
src/backends/sentry_backend_crashpad.cpp	88.60% <100.00%> (-0.35%)	⬇️
src/sentry_value.c	84.57% <0.00%> (-0.20%)	⬇️
src/sentry_logger.c	70.37% <0.00%> (ø)
src/sentry_logger.h	100.00% <0.00%> (ø)
src/sentry_options.h	100.00% <0.00%> (ø)
src/sentry_options.c	76.41% <0.00%> (+1.41%)	⬆️

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