aconfig: give commands ownership of all arguments

Pass the Cache argument to command::create_<lang>_lib functions by value
instead of by reference, to align with other commands.

The intended ownership flow is as follows:

  - main creates objects based on command line arguments
  - main hands commands ownership of the objects
  - command processes the objects
  - command gives main ownership of any generated output
  - main writes the output to file

Rationale: commands.rs is a unit testable version of main, and to the
rest of aconfig, acts as the top level entry point; main.rs exists only
to parse command line arguments and perform I/O.

Bug: 283910447
Test: atest aconfig.test
Change-Id: I1e1dea7da8ecc2bb6e2f7ee4a6df64562c148959