rcs-chat: URL scheme

[1] Official Document RCC.71 - RCS Universal Profile Service Definition Document (2017-07-12 18:57:42 +09:00) <https://www.gsma.com/futurenetworks/wp-content/uploads/2017/07/RCC.71_v2.0.pdf#page=248>

rcs-chat:<groupid>?users=<encoded list of users separated by comma>
If the list of users contains the current user, it has to be marked with a special parameter
“self=true”.

[2] Official Document RCC.71 - RCS Universal Profile Service Definition Document (2017-07-12 18:57:42 +09:00) <https://www.gsma.com/futurenetworks/wp-content/uploads/2017/07/RCC.71_v2.0.pdf#page=249>

When anonymizing a Group Chat URI, any single user in the group shall be anonymized.
Example of an anonymized group address:
rcschat:12345?users=tel%3A%252B123456789%3Falias%3DGoofy%26self%3Dtrue,tel%3A%
252B123456788%3Falias%3DSpooky,tel%3A%252B123456787%3Falias%3Wooky
becomes
rcschat:12345?users=tel%3A<HASH>%3Falias%3DGoofy%26self%3Dtrue,tel%3A<HASH>%3F
alias%3DSpooky,tel%3A<HASH>%3Falias%3Wooky