Add TextShaper API

TextShaper API provides a primitive text layout result, e.g. what glyph is used etc.

Here is the new APIs and its description

- PositionedGlyphs
This is a native instance backed object that gives layout information to developers.

- GlyphStyle
The glyph style is an object that holds the parameters that will be used for drawing.
This object is a subset of the Paint object for avoiding creating lots of Paint copy.

- TextShaper#shapeText
This does a text shaping and gives TextShaper.Result. This is a native backed primitive
shaping API.

- StyledTextShaper
This is a text shaper for a styled text. This will be the top-level developer facing
API for shaping text.

Bug: 168048923
Test: atest FontTest TextShaperTest StyledTextShaperTest
Change-Id: I2e91d1ef8503b25b28efc94da7de7cad49c4c1a9