ci(android,ios): Publish Plugin as native library

[OS-pedrogustavobilro]

Description

Add GitHub actions and scripts to allow publishing Plugins as native libraries.

This code is based on the existing code for capacitor-plugins monorepo, with a few differences:

1. No use of lerna
2. Actions now run automatically when running the release pipeline (which includes npm publishing), but only do so from main branch. In order words, only run when releasing stable versions (since with our release config non-stable versions are in next and development branches.
3. [Android] No customization of which Capacitor version to use as gradle dependency - Always based off of latest Capacitor Major - see [scripts/publish_android.sh] for more info
4. [iOS] Instead of just running pod trunk publish, it is now in a [scripts/publish_ios.sh] that does similar validations to android before attempting to publish.

Context

To allow plugins to be published as native libraries to Maven Central and CocoaPods Trunk in the new repo, as they have been in the past - Particularly relevant for Ionic Portals users.

Type of changes

• Fix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Refactor (cosmetic changes)
• Breaking change (change that would cause existing functionality to not work as expected)
• None of the above - CI changes

Platforms affected

• Android
• iOS
• Web

Tests

Refer to tests in this branch, where everything was tested except actually publishing - See successful GitHub action