CI+Lagom: Add Lagom Android CI for arm64-v8a on NDK 24 with API level 30

This will let us validate that we aren't breaking any library compile
steps for arm64.

Meta/Azure/Caches.yml

@@ -9,6 +9,8 @@ parameters:
   toolchain_ccache_path: ''
   toolchain_ccache_size: $(CCACHE_MAXSIZE)
   with_remote_data_caches: true
+  ndk_version: ''
+  with_ndk_cache: false
 
 steps:
   - script: |
@@ -75,3 +77,13 @@ steps:
         key: '"unicode_locale" | Meta/CMake/unicode_data.cmake'
         path: $(Build.SourcesDirectory)/${{ parameters.build_directory }}/CLDR
       displayName: 'UnicodeLocale Cache'
+
+  - ${{ if eq(parameters.with_ndk_cache, true) }}:
+    - bash: |
+        echo "##vso[task.setvariable variable=ANDROID_SDK_ROOT;]$ANDROID_SDK_ROOT"
+      displayName: 'Set ANDROID_SDK_ROOT'
+    - task: Cache@2
+      inputs:
+        key: '"ndk" | "$(Agent.OS)" | "${{ parameters.ndk_version }}" '
+        path: $(ANDROID_SDK_ROOT)/ndk
+      displayName: 'Android NDK Cache'