The bulk of this commit is moving the LeaderRoutineManager from the agent/consul package into its own package: lib/gort. It also got a renaming and its Start method now requires a context. Requiring that context required updating a whole bunch of other places in the code.
* Implement leader routine manager
Switch over the following to use it for go routine management:
• Config entry Replication
• ACL replication - tokens, policies, roles and legacy tokens
• ACL legacy token upgrade
• ACL token reaping
• Intention Replication
• Secondary CA Roots Watching
• CA Root Pruning
Also added the StopAll call into the Server Shutdown method to ensure all leader routines get killed off when shutting down.
This should be mostly unnecessary as `revokeLeadership` should manually stop each one but just in case we really want these to go away (eventually).
Previously a sequence of events like:
Start
Stop
Start
Stop
would segfault on the second stop because the original ctx and cancel func were only initialized during the constructor and not during Start.
