Bp2build support for sdk_version and java_version.

This CL adds java_version and sdk_version support to bp2build
converters for
   - java library
   - java binary
   - android library
   - android binary
   - android library import

Although java import doesn't support java_version and sdk_version, the
neverlink java_library wrapper around a java_import must specify a
sdk_version when targetting a device. "none" is used by convention.

Change-Id: I22a69dea2e351858368df69ed6a703b568d613ea
Bug: 215230098
Test: Presubmits