Improve correctness of SkiaCanvas::drawLayoutOnPath

Align glyph to a tangent touching SkPath in the midle of the
symbol. Previously wrong tangent crossing the path at the
beginning of the glyph was used.

Test: Ran the test app attached to the bug
Bug: 71525360
Change-Id: I310394d11e185de314f66a6b332f804188e42ed9