Introduce createCollectionWithVariation.

This lays the groundwork for variation settings support.
Since we should regard different variations of a font as different fonts, we
need to create new typefaces. To reuse the same instance of MinikinFont, as
much as possible, FontFamily::createFamilyWithVariation now reuses an
existence instance, while incrementing the reference count.

Test: minikin_tests
Bug: 33062398
Change-Id: I08e9b74192f8af1d045f1276498fa4e60d73863e

• include/minikin/FontCollection.h[diff]
• include/minikin/FontFamily.h[diff]
• include/minikin/MinikinFont.h[diff]
• libs/minikin/AnalyzeStyle.cpp[Deleted - diff]
• libs/minikin/Android.mk[diff]
• libs/minikin/FontCollection.cpp[diff]
• libs/minikin/FontFamily.cpp[diff]
• libs/minikin/FontUtils.cpp[Added - diff]
• libs/minikin/FontUtils.h[Renamed from include/minikin/AnalyzeStyle.h - diff]
• tests/data/MultiAxis.ttf[Added - diff]
• tests/data/MultiAxis.ttx[Added - diff]
• tests/unittest/Android.mk[diff]
• tests/unittest/FontCollectionTest.cpp[diff]
• tests/unittest/FontFamilyTest.cpp[diff]
• tests/util/MinikinFontForTest.cpp[diff]
• tests/util/MinikinFontForTest.h[diff]