make GetChannelByName take teamId first (#9134)

* make GetChannelByName take teamId first

I think it is more natural to accept `teamId`, then `channelName`,
given the pattern followed by other Plugin API methods and even the SQL
Store itself. The App layer seems unusual in accepting `channelName`
first.

This also re-generates the mocks fixing the parameter order for the
recently added `UserStatus` APIs.

* add GetChannelByNameForTeamName

plugin/plugintest/hooks.go

@@ -1,4 +1,4 @@
-// Code generated by mockery v1.0.0
+// Code generated by mockery v1.0.0. DO NOT EDIT.
 
 // Regenerate this file using `make plugin-mocks`.