feat: WebGL support for C# layer

[bruno-garcia]

This will superseed #329 with the final WebGL support.

This PR in the .NET SDK has the change needed to add a customer BW here: getsentry/sentry-dotnet#1450

[github-actions]

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🚫	Please consider adding a changelog entry for the next release.

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

Instructions and example for changelog

Please add an entry to CHANGELOG.md to the "Unreleased" section. Make sure the entry includes this PR's number.

Example:

## Unreleased

- WebGL support for C# layer ([#537](https://github.com/getsentry/sentry-unity/pull/537))

If none of the above apply, you can opt out of this check by adding #skip-changelog to the PR description.

Generated by 🚫 dangerJS against 11b0580

[vaind]

This was fairly outdated so I cherry-picked (and fixed) the JS files and continued in another branch, see #657. Feel free to remove the original branch feature/webgl