Re-submit "Add genrule for the current sdk proto"

This reverts commit e15e6483,
but adds embedded_launcher: true, as well as a copy of sdk.proto
as a workaround.

...which should hopefully fix the python3-issues.

Test: m cur_sdkinfo
Change-Id: I58aff4e175bd44372e9e03e67439085f08ccdc5e