[HouseKeeping] Create build in another branch while tagging

[daeus]

In order to allow people with very little frontend background could test the extension easily, we want to commit the built files into another branch. So that they could get all the necessary built files without installing node and npm.

Acceptance Criteria:

1. Built files are successfully "deploy" into a new branch "extension-build" upon tagging
2. User is able to do normal drag and drop to install the unpacked / packed extension with the built branch