Remove unsed code form Rakugo

[Jeremi360]

at top of Rakugo.gd there are banch of strings to settings that are from older versions and are no longer in use:

# Rakugo
## Setting's strings
const game_version = "addons/rakugo/game_version"
const force_reload = "addons/rakugo/force_reload"
const auto_mode_delay = "addons/rakugo/auto_mode_delay"
const typing_effect_delay = "addons/rakugo/typing_effect_delay"
const skip_delay = "addons/rakugo/skip_delay"
const rollback_steps = "addons/rakugo/rollback_steps"
const history_length = "addons/rakugo/history_length"
const narrator_name = "addons/rakugo/narrator/name"
const debug = "addons/rakugo/debug"
const save_folder = "addons/rakugo/save_folder"
const test_mode = "addons/rakugo/test_mode"

#Godot
## Setting's strings
const game_title = "application/config/name"
const main_scene = "application/run/main_scene"
const width = "display/window/size/width"
const height = "display/window/size/height"
const fullscreen = "display/window/size/fullscreen"
const maximized = "display/window/size/maximized"

[Jeremi360]

I didn't remove them all as we use few of them:

[Jeremi360]

I also clean up project.godot: