ci: added steps for publishing to openvsx and vs code marketplace

Author: adamgeorge309

.github/workflows/release.yml

@@ -51,3 +51,13 @@ jobs:
         asset_path: ./omnetpp-vscode-${{ env.VERSION }}.vsix
         asset_name: omnetpp-vscode-${{ env.VERSION }}.vsix
         asset_content_type: application/vsix
+
+    - name: Publish to Open VSX Registry
+      uses: HaaLeo/publish-vscode-extension@v1
+      with:
+        pat: ${{ secrets.OPEN_VSX_TOKEN }}
+    - name: Publish to Visual Studio Marketplace
+      uses: HaaLeo/publish-vscode-extension@v1
+      with:
+        pat: ${{ secrets.VS_MARKETPLACE_TOKEN }}
+        registryUrl: https://marketplace.visualstudio.com