Implement whoami endpoint

[anoadragon453]

Spec URL: https://matrix.org/docs/spec/client_server/r0.3.0.html#get-matrix-client-r0-account-whoami

Phase: 2

Difficulty: Easy

We receive an access token, and with that we return the user_id connected to that access token.

Summary:

• Create endpoint for GET /account/whoami in routing.go
• Return the correct user_id for the given access token. If no correct token was found, return M_UNKNOWN_TOKEN
• Create test case(s) for /account/whoami with correct and incorrect access tokens.

[turt2live]

(and make sure it works with appservices 😇 )

[anoadragon453]

@turt2live Thanks! You think the spec would mention them :P

[turt2live]

I wrote that spec, so that's more of an oversight on my part :(

/me scribbles unintelligible words on his todo list

[anoadragon453]

@turt2live matrix-org/matrix-spec-proposals#1135 ;)

[richvdh]

Ensure this endpoint works with Application Services. App services pass in ?user_id= as part of the request, so just need to hand this back.

This is true for most endpoints (and supporting it is not necessarily 'Easy'). We should probably have a separate bug to track it?

[anoadragon453]

@richvdh Good point, I'll move it out.

[anoadragon453]

Actually I'm pretty sure it's just tracked under #358.