[skshaper] Unhide legacy Shape() entry point

https://skia-review.git.corp.google.com/c/skia/+/1330016 deprecated
the previous API version and hid it behind
SK_DISABLE_LEGACY_SKSHAPER_FUNCTIONS.

That's causing build issues for clients which have the define but have
not been updated.

Temporarily unhide the legacy method to facilitate client migration.

Change-Id: I90a9da66d190d0fa19c45c81637f00942c384df4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1346656
Commit-Queue: Florin Malita <fmalita@google.com>
Auto-Submit: Florin Malita <fmalita@google.com>
Reviewed-by: Nathan Sanchez <nathanasanchez@google.com>
Commit-Queue: Nathan Sanchez <nathanasanchez@google.com>