Linux tests + coverage report with Bazel

[louwers]

Just trying out Bazel and exploring the build setup.

Two C++ unit tests now can be run with:

bazel test //test:core

[louwers]

I wanted to use the new Platforms functionality to configure which headers include and which flags to pass etc. but it turns out rules_apple does not have support for it yet: bazelbuild/rules_apple#1658

I need to find some workaround.

[louwers]

codecov.io needs to be enabled, but I don't have organization access. So the upload will fail.

I also need to enable all tests. It's just one now to get everything running end-to-end.
I'll add the rest in a separate PR.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (main@4ebb7c5). Click here to learn what that means.
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1139   +/-   ##
=======================================
  Coverage        ?   63.15%           
=======================================
  Files           ?      588           
  Lines           ?    31991           
  Branches        ?        0           
=======================================
  Hits            ?    20203           
  Misses          ?    11788           
  Partials        ?        0           

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[github-actions]

Render test results at https://maplibre-native-test-artifacts.s3.eu-central-1.amazonaws.com/4982432783-linux-gcc8-release-style.html

[github-actions]

Size test result

Old size: 8891216 bytes
New size: 8887808 bytes
Difference: +0.04%