refactor(@angular/build): run initialization tasks concurrently in library builder

Moving target project name validation before async operations allows early exit if missing. Additionally, normalizing library options, initializing xxHash, and purging the stale build disk cache concurrently via Promise.all avoids serial awaiting during builder startup.

Author: alan-agius4

packages/angular/build/src/builders/library/builder.ts

@@ -42,10 +42,6 @@ export async function* executeLibraryBuilder(
   context: BuilderContext & { signal?: AbortSignal },
 ): AsyncIterableIterator<BuilderOutput> {
   assertCompatibleAngularVersion(context.workspaceRoot);
-  await initializeHash();
-
-  // Purge old build disk cache
-  await purgeStaleBuildCache(context);
 
   const projectName = context.target?.project;
   if (!projectName) {
@@ -54,7 +50,13 @@ export async function* executeLibraryBuilder(
     return;
   }
 
-  const normalizedOptions = await normalizeLibraryOptions(context, projectName, options);
+  const [normalizedOptions] = await Promise.all([
+    normalizeLibraryOptions(context, projectName, options),
+    initializeHash(),
+    // Purge old build disk cache
+    purgeStaleBuildCache(context),
+  ]);
+
   const {
     workspaceRoot,
     projectRoot,