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_host_conversion_test.go

@@ -63,8 +63,8 @@ java_library_host {
     })`,
 			}),
 			MakeBazelTarget("java_library", "java-lib-host-2", AttrNameToString{
-				"javacopts": `["-source 1.9 -target 1.9"]`,
-				"srcs":      `["c.java"]`,
+				"java_version": `"9"`,
+				"srcs":         `["c.java"]`,
 				"target_compatible_with": `select({
         "//build/bazel/platforms/os:android": ["@platforms//:incompatible"],
         "//conditions:default": [],
@@ -77,6 +77,7 @@ java_library_host {
         "//build/bazel/platforms/os:android": ["@platforms//:incompatible"],
         "//conditions:default": [],
     })`,
+				"java_version": `"9"`,
 			}),
 		},
 	})