Use id_access_token in CS API when required

[manuroe]

Make sure we pass the token on CS APIs that need it, ie:

• inviteByThreePid: POST /rooms/$roomId/invite
• all /requestToken APIs:
  • /register/email/requestToken
  • /register/msisdn/requestToken
  • /account/3pid/email/requestToken
  • /account/3pid/msisdn/requestToken
  • /account/password/email/requestToken
  • /account/password/msisdn/requestToken

[manuroe]

With https://github.com/matrix-org/matrix-doc/blob/anoa/msc_separate_hs_api/proposals/2290-separate-threepid-bind-hs.md, it seems we will not need this token for:
- /account/3pid/email/requestToken
- /account/3pid/msisdn/requestToken
- /account/password/email/requestToken
- /account/password/msisdn/requestToken

TODO: douche check this and check requirements for others. Then, update the issue.

[anoadragon453]

The required endpoints should just be:

• POST /rooms/$roomId/invite
• POST /createRoom

The /requestToken endpoints (at least password and registration) shouldn't need it. I'll try to figure out what's up.

[BillCarsonFr]

See #3322