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

bp2build/java_library_conversion_test.go

@@ -172,10 +172,13 @@ func TestJavaLibraryJavaVersion(t *testing.T) {
 }`,
 		ExpectedBazelTargets: []string{
 			MakeBazelTarget("java_library", "java-lib-1", AttrNameToString{
-				"srcs":      `["a.java"]`,
-				"javacopts": `["-source 11 -target 11"]`,
+				"srcs":         `["a.java"]`,
+				"java_version": `"11"`,
 			}),
-			MakeNeverlinkDuplicateTarget("java_library", "java-lib-1"),
+			MakeNeverlinkDuplicateTargetWithAttrs(
+				"java_library",
+				"java-lib-1",
+				AttrNameToString{"java_version": `"11"`}),
 		},
 	})
 }