SkPDF: SkPDFFont organization changes.
SkPDFFont:
- SkPDFType1Font::populate() encode advances correctly.
- break out logically independent code into new files:
* SkPDFConvertType1FontStream
* SkPDFMakeToUnicodeCmap
SkPDFFont.cpp is now 380 lines smaller.
Expose `SkPDFAppendCmapSections()` for testing.
SkPDFFontImpl.h
- Fold into SkPDFFont.
SkPDFConvertType1FontStream:
- Now assume given a SkStreamAsset
SkPDFFont:
- AdvanceMetric now hidden in a anonymous namespace.
No public API changes.
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2221163002