Support pinning java-version as "latest"

Add a `latest` alias for the `java-version` input that floats to the newest
available stable (GA) release. It is normalized to the SemVer wildcard at the
base-installer layer and always resolves from remote (like `check-latest: true`).

List-based distributions resolve it automatically via the existing newest-first
matching. Corretto selects its newest available major; Oracle and GraalVM look up
the newest GA major via the Adoptium API and request it, failing with an actionable
error if that major isn't published yet. The jdkfile distribution rejects `latest`.

Closes #832

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

__tests__/distributors/temurin-installer.test.ts

@@ -312,6 +312,24 @@ describe('findPackageForDownload', () => {
     expect(resolvedVersion.signatureUrl).toBeDefined();
   });
 
+  it('version "latest" is normalized to the newest available version', async () => {
+    const distribution = new TemurinDistribution(
+      {
+        version: 'latest',
+        architecture: 'x64',
+        packageType: 'jdk',
+        checkLatest: false
+      },
+      TemurinImplementation.Hotspot
+    );
+    distribution['getAvailableVersions'] = async () => manifestData as any;
+    // normalizeVersion turns `latest` into the wildcard carried on `this.version`
+    const resolvedVersion = await distribution['findPackageForDownload'](
+      distribution['version']
+    );
+    expect(resolvedVersion.version).toBe('16.0.2+7');
+  });
+
   it('version is found but binaries list is empty', async () => {
     const distribution = new TemurinDistribution(
       {