Snake Plugin: Store game state on close and restore it on restart, show highscore

[JuanJakobo]

What's new

• Implements #1041 as it safes the current game state and restores it on restart
• Saves also an highscore to an file and shows the highscore on GameOver

Verification

• Open App and close it after moving a little bit around, reopen it and the state should be as before.
• Close the App when GameOver Screen is shown. The Game should restart normal.
• Crash the snake and see if the highscore is shown. Do it again with an higher score and see if it increased, further do it with a lower score to verify if it stays the same.

Checklist (For Reviewer)

• [ ] PR has description of feature/bug or link to Confluence/Jira task
• [ ] Description contains actions to verify feature/bugfix
• [ ] I've built this code, uploaded it to the device and verified feature/bugfix

[skotopes]

@DrZlo13 is currently formalizing rules for ext apps storage layout. He'll be reviewer for this PR

[DrZlo13]

@JuanJakobo Hello! I am now busy formalizing the rules for placing user files and supporting these rules in the firmware. It's enough for me for now if you put this file in "/ext/apps_data/snake_game".

[JuanJakobo]

@DrZlo13 Hi, I moved the file storage to "/ext/apps_data/snake_game".

[skotopes]

@DrZlo13 please review.

[skotopes]

Please un-draft when ready ;-) And let me know if you need any help

[fennectech]

I can't tell whether this means it was merged or is dead.

[skotopes]

@fennectech dead, PR was closed before merged