Sort api files by api scope in java_api_library

Recent changes in metalava (aosp/2704325) enforces api files passed as
inputs to generate stubs from txt to be sorted in the order from the
narrower api scope to the wider api scope. In order to comply with this
change, all api files passed as inputs to metalava invocations need to
be sorted in the respective order.

Test: m out/soong/.intermediates/packages/modules/IPsec/tests/cts/CtsIkeTestCases/android_common/e10894d3da5db41239526c9048962355/javac/CtsIkeTestCases.jar --build-from-text-stub --skip-soong-tests (Failing module from incorrect class hierarchy when building from text stub)
Bug: 295429988
Change-Id: I1eb1f4bf8fa34fd7dc8a0e4c04aa056258a975c5