Move ivert logic and trigger logic into Trigger

The base Trigger class is now responsible for inverting the trigger
state and also for signaling trigger activation to the target/indicator.

In addition the following non-function changes also occured:
 - The triggers moved into their own directory
 - The trigger code has been annotated to help lua-language-server
   deduce type information
 - AuraTrigger was moved into its own file

All these changes should make future development of other triggers easier

src/OmicronFrames.toc

@@ -9,7 +9,8 @@ main.lua
 
 types/types.lua
 types/object.lua
-types/trigger.lua
+types/triggers/trigger.lua
+types/triggers/auratrigger.lua
 types/statusbar.lua
 types/auralist.lua
 types/indicator.lua