Add JDK installation support (move from android-platform-support)

[rmarinho]

Summary

Add JDK installation support to Xamarin.Android.Tools.AndroidSdk so that consumers (MAUI DevTools CLI, IDE extensions, build tasks) can auto-install missing JDKs instead of just reporting errors.

Background

The android-platform-support (internal) repository already has a working JavaDependencyInstaller implementation that:

• Discovers available JDK versions from the Xamarin Android Manifest Feed
• Downloads Microsoft OpenJDK archives (per-platform/architecture)
• Verifies downloads via SHA-1 checksums from the manifest
• Extracts and validates the JDK installation

This capability should be moved to the public Xamarin.Android.Tools.AndroidSdk package.

Proposed API Surface

• JdkInstaller.DiscoverAsync() — find available JDK versions from the manifest feed
• JdkInstaller.InstallAsync(version, targetPath) — download, verify checksum, extract JDK
• JdkInstaller.IsValid(jdkPath) — validate an existing JDK installation

Manifest Feed

JDK archives are listed in the Xamarin Android Manifest Feed (https://aka.ms/AndroidManifestFeed/d{version}), which includes:

• Per-platform URLs (Windows, macOS, Linux)
• Per-architecture variants (x64, aarch64)
• SHA-1 checksums for download verification

Consumer

• MAUI DevTools CLI (maui android install, maui android jdk install) — see MAUI DevTools Spec PR

Related

• MAUI DevTools spec §6.8: Shared Libraries & Code Reuse

[rmarinho]

Implementation Progress

I've started work on the MAUI DevTools integration. Here's the current state for JDK support:

What exists today

• JdkInfo class provides JDK detection (finding existing installations)
• No JDK installation capability yet

Dependencies

This issue is blocked by #273 (Manifest Feed Parsing) — we need the manifest feed to resolve:

• Available JDK versions
• Per-platform download URLs (Windows/macOS/Linux × x64/arm64)
• SHA-1 checksums for verification

Proposed implementation order

1. Add manifest feed parsing for SDK/JDK download resolution (move from android-platform-support) #273 — Manifest feed parsing (prerequisite)
2. This issue (Add JDK installation support (move from android-platform-support) #270) — JDK installation using manifest data

Related work

• MAUI DevTools CLI has placeholder JdkManager that currently only does detection
• Once Add manifest feed parsing for SDK/JDK download resolution (move from android-platform-support) #273 is done, we can implement JdkInstaller.InstallAsync() properly