Add mouse input option for the third-person camera (#1011)

* Untie existing mouse logic from gyro

* A bit more mouse cleanup before I start building off it

* Rebase and last bit of cleanup

* Fix rebase mistake, don't apply invertFirstPerson to gyro or mouse input

* Remove the deprecated ImGui toast system

* Add Mouse Camera option in preparation for its use

* WIP, add mouse controls for the third-person camera

* Various helpText revisions

* Enable free camera on horseback

* Untie mouse camera and free camera options
Either being enabled now allows the underlying freecam logic to run

* Allow simultaneous C-stick and mouse input

* Combine mouse sensitivities for both aim and camera

* Add option for inverting mouse Y

* Refactor cursor visibility handling

* Tighten aim capture condition and constrain cursor to window region

* Tidying my trash

* Last bit of housekeeping so I'm satisfied

* Don't write code while sleep deprived

* Fix my sloppy merge and a few helpText updates

* Disable control stick aim when mouse aim is active

* Use same conditions for cursor grabbing as for capture

src/dusk/ui/prelaunch.cpp

@@ -699,8 +699,6 @@ Prelaunch::Prelaunch() : Document(kDocumentSource), mRoot(mDocument->GetElementB
                 return;
             }
 
-            toggle_cursor_if_gyro(false);
-
             mDoAud_seStartMenu(kSoundPlay);
             show_menu_notification();