logout returns M_UNKNOWN_TOKEN instead of M_MISSING_TOKEN

[taigaka]

Using /_matrix/client/r0/logout without an access token returns the error

M_UNKNOWN_TOKEN Access Token unknown or expired

while every other unauthorized request, including /_matrix/client/r0/logout/all returns

M_MISSING_TOKEN Missing access token.

[turt2live]

This is a synapse bug - I'll move this there.

[aaronraimist]

This was fixed