java_sdk_library: Add sdk_version for API scopes

Allow the sdk_version against which the stubs for a scope are compiled
to be specified in the module on a per scope basis.

Bug: 155164730
Test: m nothing
Merged-In: I5881e5ee7c2169c30f544882344a60a602dae917
Change-Id: I5881e5ee7c2169c30f544882344a60a602dae917
(cherry picked from commit 87a05a38)