Upload CI build artifacts to Artifactory

Bintray will be shut down in May, and JFrog suggest migrating to
Artifactory. The free tier offers 2 GB of storage, which is much
less than what we use on Bintray, so only store one build per
branch to help avoid running out of space.

.github/workflows/ci.yml

@@ -23,6 +23,56 @@ jobs:
           python3 delete_old_bintray_versions.py -g loot/libloot -b loot/snapshots/libloot -u wrinklyninja -k ${{ secrets.BINTRAY_API_KEY }} -t ${{ secrets.GITHUB_TOKEN }} -n 30
         if: github.event_name == 'push'
 
+  # Publish to Artifactory as a separate job that runs after the build jobs
+  # because we must first clean out any existing artifacts for this Git ref,
+  # and we don't want to do that as a pre-build step in case the build fails
+  # and we're left with no artifacts published.
+  publish-to-artifactory:
+    runs-on: ubuntu-18.04
+    needs: [linux, windows]
+    if: github.event_name == 'push'
+
+    steps:
+      - name: Clean up artifacts on Artifactory
+        run: |
+          curl -sfSLO 'https://raw.githubusercontent.com/Ortham/ci-scripts/2.2.0/remove_old_artifactory_files.py'
+
+          python3 remove_old_artifactory_files.py \
+            --artifactory-host loot.jfrog.io \
+            --artifactory-api-key ${{ secrets.ARTIFACTORY_API_KEY }} \
+            --artifactory-repository libloot \
+            --current-branch "${GITHUB_REF#refs/*/}" \
+            --github-repository loot/libloot \
+            --github-token ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Create empty directory for artifacts
+        run: |
+          rm -rf downloaded_artifacts
+          mkdir downloaded_artifacts
+
+      - name: Download all artifacts for this workflow from GitHub Actions
+        uses: actions/download-artifact@v2
+        with:
+          path: downloaded_artifacts
+
+      - name: Publish artifacts to Artifactory
+        shell: bash
+        run: |
+          curl -sfSLO 'https://raw.githubusercontent.com/Ortham/ci-scripts/2.2.0/percent_encode.py'
+
+          PERCENT_ENCODED_GIT_REF_NAME=$(python3 percent_encode.py "${GITHUB_REF#refs/*/}")
+
+          for ARTIFACT_DIRECTORY in downloaded_artifacts/*
+          do
+            ARTIFACT_NAME="${ARTIFACT_DIRECTORY#downloaded_artifacts/}"
+            PERCENT_ENCODED_ARTIFACT_NAME=$(python3 percent_encode.py "$ARTIFACT_NAME")
+            curl -sSfL \
+              -X PUT \
+              -T "$ARTIFACT_DIRECTORY/$ARTIFACT_NAME" \
+              -H "X-JFrog-Art-Api: ${{ secrets.ARTIFACTORY_API_KEY }}" \
+              "https://loot.jfrog.io/artifactory/libloot/${PERCENT_ENCODED_GIT_REF_NAME}/$PERCENT_ENCODED_ARTIFACT_NAME"
+          done
+
   linux:
     runs-on: ubuntu-18.04