Register JavaCompileActionContext in Bazel.

This makes --experimental_java_classpath=bazel work.

This CL is similar to bazelbuild#16636 but applies the code review feedback. (Though, I put the context registration in BazelRulesModule rather than BazelStrategyModule as JavaCompileActionContext isn't really a strategy.)

Fixes bazelbuild#16635.

src/main/java/com/google/devtools/build/lib/bazel/rules/BazelRulesModule.java

@@ -19,10 +19,13 @@
 import com.google.devtools.build.lib.analysis.ConfiguredRuleClassProvider;
 import com.google.devtools.build.lib.bazel.rules.cpp.BazelCppRuleClasses;
 import com.google.devtools.build.lib.bazel.rules.sh.BazelShRuleClasses;
+import com.google.devtools.build.lib.buildtool.BuildRequest;
+import com.google.devtools.build.lib.exec.ModuleActionContextRegistry;
 import com.google.devtools.build.lib.remote.options.RemoteOptions;
 import com.google.devtools.build.lib.rules.cpp.CcSkyframeFdoSupportFunction;
 import com.google.devtools.build.lib.rules.cpp.CcSkyframeFdoSupportValue;
 import com.google.devtools.build.lib.rules.cpp.CppOptions;
+import com.google.devtools.build.lib.rules.java.JavaCompileActionContext;
 import com.google.devtools.build.lib.rules.java.JavaOptions;
 import com.google.devtools.build.lib.runtime.BlazeModule;
 import com.google.devtools.build.lib.runtime.BlazeRuntime;
@@ -523,6 +526,14 @@ public Iterable<Class<? extends OptionsBase>> getCommandOptions(Command command)
         : ImmutableList.of(AllCommandGraveyardOptions.class);
   }
 
+  @Override
+  public void registerActionContexts(
+      ModuleActionContextRegistry.Builder registryBuilder,
+      CommandEnvironment env,
+      BuildRequest buildRequest) {
+    registryBuilder.register(JavaCompileActionContext.class, new JavaCompileActionContext());
+  }
+
   private static void validateRemoteOutputsMode(CommandEnvironment env) throws AbruptExitException {
     RemoteOptions remoteOptions = env.getOptions().getOptions(RemoteOptions.class);
     if (remoteOptions == null) {

src/test/shell/bazel/bazel_java_test.sh

@@ -325,6 +325,12 @@ function test_build_hello_world() {
   bazel build //java/main:main &> $TEST_log || fail "build failed"
 }
 
+function test_build_hello_world_reduced_classpath() {
+  write_hello_library_files
+
+  bazel build --experimental_java_classpath=bazel //java/main:main &> $TEST_log || fail "build failed"
+}
+
 function test_worker_strategy_is_default() {
   write_hello_library_files