Return a short-lived plugin API token whose aud is scoped to the given
plugin API client. The host SDK exchanges the v-air token via the broker and
caches the result; the v-air token itself is never returned.
Parameters
clientId: string
The plugin API client (token aud), e.g. "plugin-foo-api".
This is NOT the broker's confidential client id.
Returns Promise<string>
Throws
When clientId is empty or not a string.
Throws
When the user is not signed in to metatell.
Throws
When clientId is not registered (not
on the broker's allow-list).
Throws
When the exchange fails, or the host bridge
is not wired up.
Return a short-lived plugin API token whose
audis scoped to the given plugin API client. The host SDK exchanges the v-air token via the broker and caches the result; the v-air token itself is never returned.