Cleanup Agent interface

[squishykid]

Problem or use case

The Agent interface could be tidied up a bit:

• Agent.GetHookConfigPath is unused Remove unused GetHookConfigPath from Agent interface #425
• Many ways to get a list of hooks & HookHandler interface deprecated cleanup agent hook handler #427
• ParseHookEvent deprecated: Remove unused ParseHookInput from Agent interface #428
• Move hooks to hook interface: Move HookNames and ParseHookEvent to HookSupport interface #429