Tests: streamline full integration test

In 8ec632d84e3828ed50da3f83f84b48333a3b6930 full native builds for Android and iOS (using dummy bindings) were introduced. This requires a lot of dependencies and subsequently introduces long build times. This will only get worse with real functionality and additional targets (wasm and react native).

To streamline this the following changes should be added:

- [ ] Caching* for brew
- [ ] Caching* for rust / rustup multitargets
- [ ] Caching* for cargo install (for `cargo-ndk`)
- [ ] Caching* for sdkmanager
- [ ] Caching* for gradle

We should also (as soon as we integrate real functionality):

- Run native tests first
- Run integration tests only in ready-for-review PRs

Note: if the action becomes an issue due to it's weight, we can disable it until this issue has been completed.

*) In order to support the installation of development dependencies locally (through just) I did not use native actions for the dependency setup with integrated caching options