Handle continuous sessions

[untemps]

TODO: Add specifications

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Please pay attention to Sidnioulz's comments below:

Shouldn't this be memoized? What would be the performance impact if I ran, say, 5 commands in a row?

Originally posted by @Sidnioulz in https://github.com/untemps/react-vocal/pull/58#discussion_r670186260

Correct me if I'm wrong, but I should be able to completely change the commands in use without suspending the speech recognition session, right? I'm thinking of assisted typing use cases where I want to provide matching commands based on the current field / table cell.

Originally posted by @Sidnioulz in https://github.com/untemps/react-vocal/pull/58#discussion_r670186856