[package_info_plus] Fix #49 - rename platform channel id and move Java files

[miquelbeltran]

Description

As reported in #49 we have a "collision" between the original package_info and our package_info_plus in Android.

As well, we also have an undetected issue because the channel ids are exactly the same.

In this PR I move the java files to a different java package folder, and as well I rename the channel ids.

Related Issues

#49

Checklist

• 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]).
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• I updated/added relevant documentation (doc comments with ///).
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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.