Expand GrStyle's interface.

Expand GrStyle's interface.

Adds some basic getters on GrStyle as well as static const instances for fill and hairline.

Adds the ability to apply a GrStyle to a SkPath to produce an output SkPath.

Moves style key functions from GrShape to GrStyle.

Also fixes some issues with SkPath creation when applying style to GrShapes.

Adds tests that GrShape produces the correct SkPath when its GrStyle is applied.
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Review-Url: https://codereview.chromium.org/1951613002