Migrate react-native/sentry.gradle to SAGP

[krystofwoldrich]

Description

Migrating sentry.gradle to SAGP simplifies RN Android setup and ensure both source maps and native symbols are uploaded by default (currently only source maps uploaded by default).

Tasks

### Tasks
- [ ] Move sentry.gradle code to SAGP
- [ ] Create new defaults for SAGP on RN
- [ ] Add SAGP as dependency of RN SDK
- [ ] Update @sentry/wizard
- [ ] Update docs manual setup RN

Benefits

• One plugin for RN users on Android (currently two)
• One options (currently two)
• Sensible defaults (currently RN users have to change SAGP default to avoid unexpected behaviour)
  • https://docs.sentry.io/platforms/react-native/manual-setup/manual-setup/#enable-sentry-agp
  • auto-install=false need for RN
• Better support for native network requests
  • RN SDK can benefit from bytecode manipulation
• Easier to test the RN specific tasks