Fixed errors for compiling with Java17, gradle 8.1, godot 4.3 + Update payments plugin from v5.2.1 to v7.0.0

[itslenny]

This PR is a merge of #64 and #67.

This allows building using Java 17, Gradle 8.1, Google Play Billing 7.0.0, and Godot 4.3 which can successfully build and be submitted to Google Play without it complaining about the outdated Google Play Billing.

I plan to test this extensively over the course of the next week, but would love some other eyes on it as well.

[AndreCartuner]

Hey there, just in case this is still being developed; I've tried your pull req and i get some errors, first of all it breaks 2D physics engines like rapier and box2D for some reason. Next up is that it doesn't let me build despite having the requirements (java 17 etc) If you want to look it up i'm up for it if you need proof etc

platform/windows/os_windows.cpp:383 - Condition "!FileAccess::exists(path)" is true. Returning: ERR_FILE_NOT_FOUND This is the first error that than follows 100s of related ones

[syntaxerror247]

Superseded by #80. Thanks for the PR nonetheless!