Move IsScaleFactorSupported to resource_scale_factor.h

`ui::ResourceBundle::IsScaleFactorSupported` is a static method dealing
exclusively with supported resource scale factors. As such, it should
live in ui/base/resource/resource_scale_factor.*.

Additionally, remove `ui::IsSupportedScale`, a similar function that
accepts floats instead.

Bug: 1434785
Change-Id: I5fc6f1a679ed66f9906a3bd4b1d5fab3f7b06614
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4523179


Reviewed-by: Finnur Thorarinsson <finnur@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Henrique Ferreiro <hferreiro@igalia.com>
Reviewed-by: John Wu <jzw@chromium.org>
Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1147540}