doclava: include "Added in API <version>" in offline docs

Pass -metalavaApiSince to doclava when generating offline docs. This
will make the output include the "Added in API <version>" next to each
symbol, just like the online docs at DAC.

Bug: 259632341
Test: m docs # manually inspect out/target/common/docs/offline-sdk-docs-docs.zip
Change-Id: I4a6fd211ca535040d53312131df0d214d1785a0b