Dedup generating xml file for java_sdk_library

Permission XML file for java_sdk_library is generated by
java_sdk_library itself now.

And, build rule is switched to android.WriteFile since "echo -e" is
not supported from build server. (-e is printed to output)

Bug: 145474221
Test: m com.android.cronet and check its permissions xml file
     also, m org.chromium.net.cronet.xml (created dynamically)
Change-Id: Iffb119151c49bc4fe6c4386fa267cca193f37dbc