Rename LLDetectedEvent in `syntax_def_default.json` to DetectedEvent

[Martin-Pitt]

The type should be renamed to fit with the name in SLua: DetectedEvent without the LL prefix.

Was going to make this as a straightforward PR but saw there was a bunch of other related things that I wasn't sure how to handle: LLDetectedEventHandler/LLDetectedEventName/LLNonDetectedEventName

[WolfGangS]

Really this needs to be done here https://github.com/secondlife/viewer/blob/project/lua_editor/indra/newview/app_settings/types_lua_default.xml

As the syntax json is created from the output of that really.