feat: Add support for participant name, metadata, and attributes

[MahmoudHemaid]

Summary

This PR introduces support for additional participant information and improves the token generation process:

• Adds a new input for participant_name, separate from participant_id, to allow specifying a display name for participants.
• Adds support for custom metadata (string) and attributes (key-value pairs) for participants.
• Introduces a new AttributesEditor component for managing participant attributes in the UI.
• Changes the /api/token endpoint from GET to POST and updates it to accept the new fields in the request body.
• Updates user settings and configuration to include participant_name, metadata, and attributes.
• Refactors the connection logic to send the new fields when requesting a token.
• Updates the backend API to handle the new POST request and fields.
• Ensures backward compatibility by defaulting to generated values if fields are not provided.

Screenshot

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[bcherry]

this is great! I've got a couple nitpicks on the UX but I'll just merge as-is and address them in #144