Add rsp and srcjar support to kotlinc build rule

Rsp files are supported through helper script (gen-kotlin-build-file.sh)
that generates the kotlinc module/build xml file.

Since rsp files are supported, I've added ExtractSrcJarsCmd step
to handle srcjars extraction.

Minor reorderings to make sure that TransformKotlinToClasses
recives only .java and .kt files when called from Module.compile.

Bug: 73281388
Test: make -j hidl-doc
Change-Id: I5a40b914569018dc529903a7f2864a5aeae838e5
diff --git a/java/config/config.go b/java/config/config.go
index 75176c9..b5e574e 100644
--- a/java/config/config.go
+++ b/java/config/config.go
@@ -83,6 +83,8 @@
 	pctx.SourcePathVariable("Ziptime", "prebuilts/build-tools/${hostPrebuiltTag}/bin/ziptime")
 
 	pctx.SourcePathVariable("ExtractSrcJarsCmd", "build/soong/scripts/extract-srcjars.sh")
+	pctx.SourcePathVariable("GenKotlinBuildFileCmd", "build/soong/scripts/gen-kotlin-build-file.sh")
+
 	pctx.SourcePathVariable("JarArgsCmd", "build/soong/scripts/jar-args.sh")
 	pctx.HostBinToolVariable("SoongZipCmd", "soong_zip")
 	pctx.HostBinToolVariable("MergeZipsCmd", "merge_zips")