This commit updates the `Deno.Kv` API to return the new commited
versionstamp for the mutated data from `db.set` and `ao.commit`. This is
returned in the form of a `Deno.KvCommitResult` object that has a
`versionstamp` property.
This commit adds unstable "Deno.openKv()" API that allows to open
a key-value database at a specified path.
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Co-authored-by: Luca Casonato <hello@lcas.dev>
Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>
