chore: add 'build:watch' action

E.g start example in one terminal `npm run watch` and the main lib in another `npm run build:watch` and have both update on change.

Author: mblarsen

package.json

@@ -27,6 +27,7 @@
  "scripts": {
  "prebuild": "rm -rf ./dist",
  "build": "microbundle build --tsconfig ./tsconfig.json --name VueBrowserAcl",
+ "build:watch": "microbundle watch --tsconfig ./tsconfig.json --name VueBrowserAcl",
  "test": "jest --config jest.config.json",
  "test:watch": "jest jest --config jest.config.json --watchAll",
  "version": "npm run build && git add -A ./dist",