[IMPROVE] Add user roles to Jitsi token

[laliluna]

Proposed changes (including videos or screenshots)

Adding the user roles to the token allows Jitsi prosody plugins like https://github.com/nvonahsen/jitsi-token-moderation-plugin/issues to determine the user role in a Jitsi conference. Though this plugin uses a different field in the token, IMHO adding the roles to the user object fits RocketChat structure better.

Issue(s)

Fixes #17563

Steps to test or reproduce

• Enable jitsi conference with token authentication to a non existing URL of a video server
• use a dummy ID and secret
• once the conference link is opened, copy the token to jwt.io
• it should include the roles or at least an empty array

Further comments

[CLAassistant]

All committers have signed the CLA.

[dionisio-bot]

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