Copy files related to sdk dev tool(activity_actions.txt, and etc.) from

offline-sdk

Originally these files were dumped to out/target/common/docs. However,
three modules(offline-sdk, offline-sdk-referenceonly, and
offline-system-sdk-referenceonly) generate these files with the same
name which might cause the problem that these files got overwritten back
and forth.

Test: m -j out/target/common/docs/offline-sdk-timestamp
Bug: b/70351683
Change-Id: I9badab5243f0d2a14bd55e561661483365b677c2