Add a function for VINTF test to get shipping API level

If ro.product.first_api_level is 0, assume the device is a newly
launched product. The test case determines its shipping API level by
ro.build.version.sdk which is defined by the system image.

Bug: 77142177
Test: vts-tradefed run commandAndExit vts -m VtsTrebleVendorVintfTest
Change-Id: I2202049f38aea15fe90e9a2d3152aeb0fd226464
Merged-In: I2202049f38aea15fe90e9a2d3152aeb0fd226464
3 files changed