Add support for Android D8 (8.1.56) (#5756)

Adds D8Compiler, which applies to the Android Java and Android Kotlin
languages. D8Compiler instantiates a JavaCompiler or KotlinCompiler
using the java/kotlin dependencies' paths for D8 in the infra repo.

compiler-finder.ts has been updated to allow for duplicate compiler IDs
for 'android-java' and 'android-kotlin', as it is expected that the
compilers used for these languages is the same.

app.ts

@@ -73,6 +73,9 @@ import type {Language, LanguageKey} from './types/languages.interfaces.js';
 // Used by assert.ts
 global.ce_base_directory = new URL('.', import.meta.url);
 
+// Used by d8.ts
+global.handlerConfig = null;
+
 (nopt as any).invalidHandler = (key, val, types) => {
     logger.error(
         `Command line argument type error for "--${key}=${val}", expected ${types.map(t => typeof t).join(' | ')}`,
@@ -562,7 +565,8 @@ async function main() {
 
     const healthCheckFilePath = ceProps('healthCheckFilePath', false);
 
-    const handlerConfig = {
+    // Exported to allow compilers to refer to other existing compilers.
+    global.handlerConfig = {
         compileHandler,
         clientOptionsHandler,
         storageHandler,
@@ -575,8 +579,8 @@ async function main() {
         contentPolicyHeader,
     };
 
-    const noscriptHandler = new NoScriptHandler(router, handlerConfig);
-    const routeApi = new RouteAPI(router, handlerConfig);
+    const noscriptHandler = new NoScriptHandler(router, global.handlerConfig);
+    const routeApi = new RouteAPI(router, global.handlerConfig);
 
     async function onCompilerChange(compilers) {
         if (JSON.stringify(prevCompilers) === JSON.stringify(compilers)) {