[typescript] Update storage typings

[squirly]

This cleans up the storage typescript typings by adding and removing methods, including documentation, and consolidating types.

[Salakar]

@squirly thanks for putting this together, we'll look at getting this in for v5 👍

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[Salakar]

@squirly any chance you can rebase against master and fix the merge conflicts?

Thanks

[CLAassistant]

All committers have signed the CLA.

[Salakar]

@squirly thanks for updating. The analyse workflow on CI is passing (validates types) so I'm happy to merge this. Thanks again!