Support IndexedDB for service worker

[pi0]

Service workers don't allow localStorage, which we can use IndexedDB instead.

[MaxGfeller]

I'm thinking of using unstorage, especially for its clean interface, over localForage.js for an offline first web project. However, IndexedDB support is essential, thus my question: what's the current state on this? Is there something i can help with? Would it be possible to use watch(callback), too somehow (for cross-tab functionality)?

[pi0]

@MaxGfeller We are mostly busy with other tasks. If you mind opening a PR I can help and have it sooner :)

[MaxGfeller]

Alright, i see what i can do 👍🏻 Thank you.

[itpropro]

IndexedDB support was added with #221