* 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
update api mocks
Generated new hooks
ChannelHasJoinedChannel Implementation
User Left Team/Channel Hook; User Joined Team Hook Implementation
Update RPC Client and Mocks
gofmt
go tests fix
Add Config API Methods
codegne
Add Channel Has Been Created Hook
Fix ChannelHasBeenCreated hook
fix missing context param
fix duplicate hooks; remove redudandcy
* Adding blank request context to plugin hooks for future use.
* Rename RequestContext to Context
* Adding context to ServeHTTP and ExecuteCommand
* Fixing import cycle in test.
* tie back-end plugins together
* fix comment typo
* add tests and a bit of polish
* tests and polish
* add test, don't let backend executable paths escape the plugin directory
* begin backend plugin wip
* flesh out rpcplugin. everything done except for minor supervisor stubs
* done with basic plugin infrastructure
* simplify tests
* remove unused test lines
