Migrate CircleCI to GitHub Actions (#2716)

Co-authored-by: Joseph Heck <j_heck@apple.com>

.github/actions/setup-macos/action.yml

@@ -0,0 +1,31 @@
+name: 'Setup macOS Environment'
+description: 'Install dependencies for macOS builds'
+
+inputs:
+  install-mpi:
+    description: 'Whether to install MPI'
+    required: false
+    default: 'true'
+    type: boolean
+  python-version:
+    description: 'Python version to use'
+    required: false
+    default: '3.10'
+
+runs:
+  using: "composite"
+  steps:
+    - name: Install Homebrew packages
+      shell: sh
+      if: inputs.install-mpi == 'true'
+      run: /opt/homebrew/bin/brew install openmpi
+    
+    - name: Verify MetalToolchain installed
+      shell: bash
+      run: xcodebuild -showComponent MetalToolchain
+    
+    - name: Setup uv
+      uses: astral-sh/setup-uv@v6
+      with:
+          python-version: ${{ inputs.python-version }}
+          activate-environment: true