move extension npm package files & add release automation

Signed-off-by: Jari Kolehmainen <jari.kolehmainen@gmail.com>

src/extensions/npm/extensions/.gitignore

@@ -1,2 +0,0 @@
-dist/
-__mocks__/

src/extensions/npm/extensions/package.json

@@ -1,31 +0,0 @@
-{
-  "name": "@k8slens/extensions",
-  "productName": "OpenLens extensions",
-  "description": "OpenLens - Open Source Kubernetes IDE: extensions",
-  "version": "6.0.0",
-  "copyright": "© 2022 OpenLens Authors",
-  "license": "MIT",
-  "main": "dist/src/extensions/extension-api.js",
-  "types": "dist/src/extensions/extension-api.d.ts",
-  "files": [
-    "dist/**/*.ts",
-    "__mocks__/*.ts",
-    "dist/**/*.js"
-  ],
-  "author": {
-    "name": "OpenLens Authors"
-  },
-  "dependencies": {
-    "@material-ui/core": "^4.12.3",
-    "@types/node": "^16.11.58",
-    "@types/react": "^17.0.45",
-    "@types/react-dom": "^17.0.16",
-    "@types/react-router": "^5.1.18",
-    "@types/react-router-dom": "^5.3.3",
-    "conf": "^7.0.1",
-    "mobx": "^6.5.0",
-    "mobx-react": "^7.3.0",
-    "react-select": "^5.3.2",
-    "typed-emitter": "^1.3.1"
-  }
-}