Add jwt create command and createJwtToken endpoint. Closes #882

[garrytrinder]

No description provided.

[waldekmastykarz]

Noticed one more thing: if you specify a claim with the same name as one of the options (eg. sub), the token generator adds it to the collection of values rather than replacing the value. In some cases (again sub) this leads to incorrect types (sub is expected to be a string, but becomes string[]). Not sure if it's an issue, but perhaps something for us to include in remarks for clarity.

Repro:

$devproxy jwt create -n Steve -a 123 -r App.Read.All -r App.Write.All -s Foo Bar -i bob --claims "aud 456" --claims "sub Jack"

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[waldekmastykarz]

Marking as draft until we add the API

[waldekmastykarz]

Awesome!