[gSender PR#233] EventTrigger Refactor

– configStore now stores events as a map
– event name => event object (ex. gcode:start => { enabled: true, commands: 'X0', .... })
– there are constants for each of these names to increase maintainability
– migration has been written to convert old format .sender_rc (array of events) to new format (events object)
– since events are in a map and there can only be one event per key, therefore EventTrigger has been rewritten to reflect that
– this includes more general functions where the user passes a variable to specify (ex. hasEnabledEvent(PROGRAM_START) to get the enabled property of the gcode:start event)
– updated api to work with new data structure
– also added clearAll api for support – deletes all events at once
– changed import function to delete all events before adding new ones
– prevents old events from carrying over if they do not get overwritten by the new file
– bug fixes
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all code that comes after events are in feederCB, so no changes were made there