Reactivated decimal point replacement for InputScalar, SliderScalar and DragScalar

[GamingMinds-DanielC]

As requested in #6719, here is a PR that reintroduces decimal point replacement (added in a1a7a1b, lost in 4a24264) without adding any other filtering. The fix is quite simple, but did require an additional internal flag.

[ocornut]

I think I'm fine with it. Bits 21 to 25 are also unused and anything private we have some extra freedom to move it elsewhere if needed. Thanks!
But I'm now confused why this section of the "widgets_inputtext_filters" test didn't trigger:
https://github.com/ocornut/imgui_test_engine/blob/main/imgui_test_suite/imgui_tests_widgets_inputtext.cpp#L976

#if IMGUI_VERSION_NUM >= 18983
        ctx->ItemClick("decimal");
        ctx->KeyCharsReplaceEnter(".,.,");
        IM_CHECK_STR_EQ(vars.Decimal.c_str(), "....");
#endif

Will try to investigate later when I have time.

[GamingMinds-DanielC]

But I'm now confused why this section of the "widgets_inputtext_filters" test didn't trigger:

That test is on an input with the necessary filter flags given, so the replacements were not deactivated in this test and it wasn't broken as a result. SliderScalar and DragScalar didn't forward any filter flags to the temporary input anymore, that's why they were missing the replacement as well. This test doesn't cover those cases.

[ocornut]

This is merged, thank you. I have renamed the internal flag to ImGuiInputTextFlags_LocalizeDecimalPoint as it seemed a bit clearer what the intent was.

[ocornut]

FYI in today's change the storage of io.PlatformLocaleDecimalPoint has moved:
GetIO().PlatformLocaleDecimalPoint --> GetPlatformIO().Platform_LocaleDecimalPoint