feat: Add action to install dfx and its corresponding test

.github/workflows/tests/dfx-action.yml

@@ -0,0 +1,11 @@
+on: [push]
+
+jobs:
+  test_dfx_action:
+    runs-on: ubuntu-latest
+    name: Test the dfx action (action.yml)
+    steps:
+      # To use this repository's private action, you must check out the repository
+      - name: Checkout
+        uses: actions/checkout@v3
+      - uses: ./

action.yml

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+name: 'Install dfx'
+description: 'Install the dfx utility at a particular version'
+inputs:
+  dfx-version:
+    description: >
+      The dfx version to install. This value will be used to populate
+      the DFX_VERSION variable that will be handled by the installation
+      script "install.sh".
+    default: '0.14.1'
+
+runs:
+  using: composite
+  steps:
+    - name: Install dfx
+      shell: sh
+      run: DFX_VERSION=${{ inputs.dfx-version }} sh -ci "$(curl -fsSL https://internetcomputer.org/install.sh)"