[skottie] Add kBottom text alignment extension

Introduce a new Shaper::Valign enum to support aligning the shaped text
visual bottom with the text box bottom.

This option corresponds to JSON prop sk_vj: 2.

kResizeToFit (used to be sk_vj: 2) is now bumped to sk_vj: 3.

Change-Id: Ib1621a21a42bfc21c99826e203c587a3fdc663dc
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/215821
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
2 files changed