Add React Native 0.75 tests

[yousif-bugsnag]

Goal

Adds React Native 0.75 tests to CI, and updates some test features around native exceptions to account for differences in behaviour in 0.75:

On Android, errors from native promise rejections now have the Error.name field populated with the native exception class, so the errorClass of the resulting event is now set to the native exception (e.g. java.lang.RuntimeException) instead of the default Error (see native-stack.feature).

As part of this work, 0.73 tests have been moved to the full pipeline, and 0.71 and 0.72 test fixtures are now generated dynamically (these were previously using static test fixtures).

Testing

Covered by CI

[github-actions]

@bugsnag/browser bundle size diff

	Minified	Minfied + Gzipped
Before	44.21 kB	13.51 kB
After	44.21 kB	13.51 kB
±	No change	No change

code coverage diff

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