Convert pom2mk to pom2bp that writes out Android.bp files instead
of Android.mk files. pom2mk stays for now until the last users
of it are cleaned up.
Bug: 78300023
Test: cd prebuilts/sdk/current/support && pom2bp -regen Android.mk
Change-Id: I584d63c4228bad32f9e1914b06bde807078d6a55
