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/document.cpp

@@ -5,7 +5,6 @@
 
 #include "Z2AudioLib/Z2SeMgr.h"
 #include "m_Do/m_Do_audio.h"
-#include <imgui.h>
 
 namespace dusk::ui {
 namespace {
@@ -107,7 +106,6 @@ bool Document::visible() const {
 
 bool Document::handle_nav_command(Rml::Event& event, NavCommand cmd) {
     if (cmd == NavCommand::Menu) {
-        toggle_cursor_if_gyro(!visible());
         mDoAud_seStartMenu(visible() ? kSoundMenuClose : kSoundMenuOpen);
         toggle();
         return true;
@@ -115,17 +113,4 @@ bool Document::handle_nav_command(Rml::Event& event, NavCommand cmd) {
     return false;
 }
 
-void Document::toggle_cursor_if_gyro(bool cursor_enabled) {
-    if (dusk::getSettings().game.gyroMode.getValue() == GyroMode::Mouse)
-    {
-        if (cursor_enabled) {
-            ImGui::GetIO().ConfigFlags &= ~ImGuiConfigFlags_NoMouseCursorChange;
-            SDL_ShowCursor();
-        } else {
-            ImGui::GetIO().ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange;
-            SDL_HideCursor();
-        }
-    }
-}
-
 }  // namespace dusk::ui