Generate SBOM of the target product in file sbom.spdx.json in product out directory.

Original aosp/2374663 was reverted, so this change cnotains the implementation but disabled by default and SBOM will not be built by default with "m dist".

The feature will be enabled later in small CLs after running tests successfully in forrest.

Test: m sbom
Test: m dist
Test: on aosp, lunch aosp_bluejay-userdebug && m dist
Bug: 266726655
Change-Id: I926d0f97f3a0330ef61d059f12ea660005d370e6