[uniffi] Rename commit to key_update

[mgeisler]

Issues:

Addresses #81.

Description of changes:

When discussing this internally, the feeling was that commit would mostly be used to refresh keys. The name key_update would thus be more descriptive.

Call-outs:

Since the method can also be used to commit received proposals (if/when we support them), the current name might be better?

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT license.

[mgeisler]

Since the method can also be used to commit received proposals (if/when we support them), the current name might be better?

The changes in the tests show this a bit, but I'll let people here discuss 😄

[mulmarta]

I'm not so sure about this one...

1. This could have 2 purposes: PCS as key_update indicates or committing received proposals
2. Depending on your commit_options and received proposals, this may NOT update any keys. E.g. if you received add proposals and your commit_options don't enforce path, then this will end up being a partial commit i.e. it doesn't update any keys

[beurdouche]

Without having looked into this much, a side note is that we should avoid non standard terminology as much as possible.

[mgeisler]

Thanks for the feedback! Let me close this for now since it doesn't sound like a good idea.