Some changes to support SBOM generation for b build unbundled APEXs.

1) Use output file path of installed files in build system since there is no PRODUCT_OUT in Bazel
2) Use CONTAINS to describe the relationship between a APEX and files it contains
3) Generate SBOM of APEXs, which is similar to SBOM of products

Bug: 275472038
Test: CIs
Change-Id: I41622366e5e6ed9dc78cca7bc7bb69a1f8f9bd9f