(GH-337) Update vscode-languageclient to 5.1.0

This commit updates the vscode-languageclient node module to 5.1.0.  This is
needed for more recent LSP features.

Author: glennsarti

package-lock.json

@@ -443,7 +443,7 @@
     "gulp-decompress": "^2.0.2"
   },
   "dependencies": {
-    "vscode-languageclient": "4.4.0",
+    "vscode-languageclient": "5.1.0",
     "vscode-extension-telemetry": "^0.0.15",
     "viz.js": "~1.7.0",
     "vscode-debugprotocol": "^1.19.0",