feat(android): add setRate

[erisu]

Platforms affected

android

Motivation and Context

• Split task from Add support for setRate on Android. Fix setRate on iOS when seeking. #196
• Rebased Add support for setRate on Android. Fix setRate on iOS when seeking. #196 with current main branch.
• Updates README to describe API requirement for setRate.
• Reverted & updated the Media.prototype.setRate conditional check to include Android.
  • The plugin also supports the Windows & Browser platforms but setRate was never previously mentioned to support those platforms.

Closes #196
Closes #296
Closes #152
Resolves #223

Description

See #196 for more details

Testing

n/a

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary