onDialogueResponse implementation

Applied recommended edits to !4028 (closed) by @psyfl, to convert from an engineHandler to an eventHandler. Evil Eye confirmed this builds correctly with the latest commit. This roughly follows the !3555 (merged) Dead event implementation. All credit goes to Psyfl and Evil Eye for their respective MRs.

Original description by Psyfl

There is a popular Morrowind mod in development, Voices of Vvardenfell (VoV), which adds voice acting to the entire game: https://www.nexusmods.com/morrowind/mods/52279.

Previously, the mod only worked with MWSE, because OpenMW's Lua API lacked some of the necessary functionality. I have decided to add the required functionality in this PR which allows the mod to support OpenMW:

onInfoGetText event - fires whenever a new line of dialogue script appears on the dialogue menu.