bp2build converts java_genrule and java_genrule_host

Bp2build currently supports building genrules for cc modules, but does
not support building java_genrule* modules. This commit adds this
functionality.

Bug: 213480907
Test: go test ./bp2build
Change-Id: I473196c5bcf5582ba0c8faa65b5005f81ac973a4
diff --git a/genrule/genrule.go b/genrule/genrule.go
index c3e3ba5..1679a57 100644
--- a/genrule/genrule.go
+++ b/genrule/genrule.go
@@ -862,7 +862,7 @@
 		cmd = strings.Replace(*m.properties.Cmd, "$(in)", "$(SRCS)", -1)
 		cmd = strings.Replace(cmd, "$(out)", "$(OUTS)", -1)
 		genDir := "$(GENDIR)"
-		if ctx.ModuleType() == "cc_genrule" {
+		if t := ctx.ModuleType(); t == "cc_genrule" || t == "java_genrule" || t == "java_genrule_host" {
 			genDir = "$(RULEDIR)"
 		}
 		cmd = strings.Replace(cmd, "$(genDir)", genDir, -1)