[package_info_plus] Migrate Android part to Kotlin

[vbuberen]

Description

Continue series of PRs on migrating Plus plugins Android parts to Kotlin.
This PR is based a branch which is based on #669 to have proper formatting for different languages.

Checklist

Before you create this PR confirm that it meets all requirements listed below by checking the relevant checkboxes ([x]).
This will ensure a smooth and quick review process. Updating the pubspec.yaml and changelogs is not required.

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• My PR includes unit or integration tests for all changed/updated/fixed behaviors (See Contributor Guide).
• All existing and new tests are passing.
• I updated/added relevant documentation (doc comments with ///).
• The analyzer (flutter analyze) does not report any problems on my PR.
• I read and followed the Flutter Style Guide.
• I am willing to follow-up on review comments in a timely manner.

Breaking Change

Does your PR require plugin users to manually update their apps to accommodate your change?

• Yes, this is a breaking change (please indicate a breaking change in CHANGELOG.md and increment major revision).
• No, this is not a breaking change.

[nohli]

Is it possible to add tests for the native part?

[vbuberen]

Is it possible to add tests for the native part?

Yes, it is possible. It is something I want to do in the following PRs, since target these Migration ones to be just a switch of language without additional changes.

[miquelbeltran]

Looks good!