[android] install Chocolatey if not installed

Installs the Chocolatey package manager if it is not already installed
on the system. This is currently needed for the Azure runners but not
for GitHub runners, where Chocolatey is pre-installed.

.github/workflows/swift-toolchain.yml

@@ -321,6 +321,9 @@ jobs:
           components: 'Microsoft.VisualStudio.Component.VC.Tools.x86.x64;Microsoft.VisualStudio.Component.VC.Tools.ARM64'
           arch: amd64
 
+      # TODO(issues/205): Preload Chocolatey package manager on Azure images so we can remove this step.
+      - uses: andrurogerz/ensure-chocolatey@v1
+
       - name: Install Flex and Bison Tools
         run: choco install winflexbison3
 
@@ -402,6 +405,9 @@ jobs:
           components: 'Microsoft.VisualStudio.Component.VC.Tools.x86.x64;Microsoft.VisualStudio.Component.VC.Tools.ARM64'
           arch: ${{ matrix.arch }}
 
+      # TODO(issues/205): Preload Chocolatey package manager on Azure images so we can remove this step.
+      - uses: andrurogerz/ensure-chocolatey@v1
+
       - name: Install Flex and Bison Tools
         run: choco install winflexbison3