ImDrawList: small debug-mode optimization when calling AddRect() without rounding + Selectable: small debug-mode optimization.

# Conflicts:
#	imgui_widgets.cpp

Revert "IO: ImGuiMod_Shortcut (Ctrl/Cmd depending on platform) is reflected in io.KeyMods. (#5923, #456)"

This reverts commit b8f93a8f. Too breaking for user.

Clipper: Fixed a bug if attempt to force-include a range which matches an already included range. (#3841)

Ties fixing f422e782 in docking: iterating root windows was incorrect. Will be faster to lazily merge in RenderDimmedBackground() rather than iterate all.

Slider: fixed support for ImGuiItemFlags_ReadOnly/ImGuiSliderFlags_ReadOnly although it is technically unused/undocumented. (#6758)

Amend fdc526e8

Clipper: Renamed IncludeRangeByIndices()/ForceDisplayRangeByIndices() to IncludeItemsByIndex(). (#6424, #3841)

Single item version added in prevous commit (20005377) renamed to IncludeItemByIndex() too.

Examples: Emscripten+webgpu: Fixed WGPUInstance creation process + use preferred framebuffer format. (#6640, #6748)

CloseButton, CollapseButton: don't include FramePadding into size. Use ItemInnerSpacing.x between title bar buttons. (#6749)

Amend 6c3697f6

Amend 13f71833

InputFloat, SliderFloat, DragFloat: always turn both '.' and ',' into the current decimal point character. (#6719, #2278)

IO: fix writing to incorrect union section for MouseSource in AddMousePosEvent and AddMouseButtonEvent. (#6727, #2702)

Technically may have had no side-effects unless non-standard alignment used.

e.g. WebGPU users use a similarly named functions from GLFW backend.

Amend f422e782

Tables: Made it possible to use SameLine(0,0) after TableNextColumn() or TableSetColumnIndex() in order to reuse line height from previous cell.

Nav, TreeNode: Pressing Left with ImGuiTreeNodeFlags_NavLeftJumpsBackHere now goes through proper navigation logic: honor scrolling and selection. (#1079, #1131)

Added a stack for this purpose which other features might build on (e.g. #2920). However this is currently gated by many tests and not a performance concern, but making stack happen all the time may be undesirable.

Amend 4d6fbaff.

Metrics: Fixed "Drawlists" section and per-viewport equivalent appearing empty (regression from c649aca2).

(#6597, #6475, #6167, #5776, #5109, #4763, #3515, #1860)