Make module apis dist their output

Only populate the targets and dir attributes. The output name
will be autopopulated to the filename, which differs by module.

Bug: 149293194
Test: m dist sdk && find out/dist/apistubs -name 'framework-*.txt'
Change-Id: I8502eb90a10d8b1ca998c2eba5646c662638ce3f
Merged-In: I8502eb90a10d8b1ca998c2eba5646c662638ce3f
(cherry picked from commit a92a23bc)