Add AS support to common.MakeAuthAPI

[APwhitehat]

• Integrate Add app service authentication functions #433 into common.MakeAuthAPI
• Update clientapi.routing to utilize the AS support.
• Make other Components work ok with the new common.MakeAuthAPI, Add "TODO" to help their migration.

[erikjohnston]

Couple of comments:

1. We probably want to refactor MakeAuthAPI, its got too many parameters as it is and its confusing
2. I wonder if we should make an authtypes.Device for AS users?

[APwhitehat]

1. I agree.
2. I thought AS users do not have a device. Did you mean a dummy device with AS service's AccessToken & userID ?

[APwhitehat]

Once matrix-org/gomatrixserverlib#92 gets merged, we can remove the "AS_Device" with a const.

[anoadragon453]

API endpoints such as this one:

dendrite/src/github.com/matrix-org/dendrite/clientapi/routing/createroom.go

Line 160 in 7844008

profile, err := accountDB.GetProfileByLocalpart(req.Context(), localpart)

still check for information from the accountDB, which fails due to an account not actually existing.

What do you think of the solution of just creating a sender_localpart account on startup for each appservice if it doesn't already exist?

[anoadragon453]

So #505 solves the generate AS sender_localpart user problem. It may or may not replace any commits on this PR.