* Support for key/value attributes on Participant
Key/value attributes lets us:
* allow various components to provide more information about the participant (i.e. SIP including the phone number)
* allow Agents to communicate their own status to the end user via RTC
* enable applications to update specific fields without overriding others
* generated protobuf
* Attribute support for SIP.
* generated protobuf
* generated protobuf
* allow specifying attributes during token generation
* Remove sip prefix and rename phone number attrs.
* regenerate protos
* update tests
* add kv attrs to sip token
* add attribute test
* changeset
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Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Denys Smirnov <dennwc@pm.me>
