This PR:

• Introduces a custom test runner, that can be executed directly from code, and bumps gdUnit4 to required commit.
• Updates CI to use the new test runner, since it improves readability in GH logs.
• To initiate tests, the demo project expects the following environment variables to be set:

  SENTRY_TEST=1
  SENTRY_TEST_INCLUDE="res://test/suites/"   # ";"-separated list of files and/or directories

  • Additionally, these variables can be set via Android extent extras using the same names.
• Adds a tool button to run tests straight from the demo project for convenience.
• Adds a script to run tests on Android on a locally connected device.
• Adjusts tests for Android platform specifics, and removes mobile tests, which are no longer needed.
• Depends on chore: Use threads interface on Android for script stack traces #436

#skip-changelog