Storage refactor

[listen1]

What is this PR about

indexed db now is only choice for storage layer, which may cause some problems:

• get key value pair using indexed has worse performance than get using localstorage
• one requirement for desktop users is green lite version (which means you can copy-parse directory to use software anywhere), so indexed db storage will replaced with file or sqilte api.

so i'm trying to move all call to indexed db to models directory, by call model member functions. It will seperate business logic from stoarge layer and we can have better control about peresistancy problems.

Progress

• settings
• playerlist
• tracks

[listen1]

v3 is delayed for this pr. Because migrate really need so much modification and testing.

For v3 publish in time, I'm consider that avoid migrate in v3, still use v2 storage, which makes it more easy to publish.

So this PR will be paused unless plan changes.