extension: Restore vsce package as a devDependency

The parent commit added this package back, which defaulted to adding it
as a regular dependency.

Signed-off-by: Marco Miller <marco.miller@ericsson.com>

Author: marco-miller

package.json

@@ -60,7 +60,6 @@
         "test": "node ./out/test/runTest.js"
     },
     "dependencies": {
-        "@vscode/vsce": "^2.19.0",
         "tree-kill": "^1.2.2",
         "tsp-typescript-client": "next"
     },
@@ -72,6 +71,7 @@
         "@typescript-eslint/eslint-plugin": "^5.59.1",
         "@typescript-eslint/parser": "^5.59.1",
         "@vscode/test-electron": "^2.3.0",
+        "@vscode/vsce": "^2.19.0",
         "eslint": "^8.39.0",
         "glob": "^8.1.0",
         "mocha": "^10.2.0",