Audit and/or add validation to endpoints in synapse/rest/client/account.py

[DMRobertson]

Processed

• EmailPasswordRequestTokenRestServlet
• PasswordRestServlet
• DeactivateAccountRestServlet
• EmailThreepidRequestTokenRestServlet
  • The above covered by Use Pydantic to systematically validate a first batch of endpoints in synapse.rest.client.account. #13188
• MsisdnThreepidRequestTokenRestServlet
• AccountStatusRestServlet
  • The above covered by A second batch of Pydantic models for rest/client/account.py #13687
• ThreepidAddRestServlet
• ThreepidBindRestServlet
• ThreepidUnbindRestServlet
• ThreepidDeleteRestServlet
  • The above covered by A third batch of Pydantic validation for rest/client/account.py #13736

Todo

• AddThreepidMsisdnSubmitTokenServlet
  • The above covered by Last batch of Pydantic for synapse/rest/client/account.py #13832

No action

• AddThreepidEmailSubmitTokenServlet, GET only
• WhoamiRestServlet, GET only
• ThreepidRestServlet
  • GET: nothing to do
  • Going to ignore POST body: it's deprecated and seemingly unused