Updated ImGui to v1.91.9

[adriengivry]

Description

Updated ImGui to v1.91.9-docking.

The goal of this update is also to keep ImGui as "vanilla" as possible, instead of modifying its source code like we did in the past.

Also updated the InputManager to expose GetMouseScroll, since ImGui::GetScroll function is broken(returns 0.0f).

• Exposed the new GetMouseScroll method to Lua
• Updated the lua scripting API (Inputs) to reflect the changes

Related Issues

Fixes #121

To-Do

• Address missing ImGui::GetIO().DisableMouseUpdate (was added by us to ImGui). Wondering if there is a better way to handle that without modifying ImGui's sources
• Mouse scroll doesn't work anymore
• Address forceHover not used with plots (PlotHistogram and PlotLines). I recall it was also custom code added to ImGui, can we do without it? follow-up issue: [Regression] Implement a system to programmatically highlight a portion of a plot #448
• Update layout.ini

[litelawliet]

Just to be sure, is it version 1.91.9 or is it 1.91.9b ?

[adriengivry]

Just to be sure, is it version 1.91.9 or is it 1.91.9b ?

Not b I guess