Automatically build and deploy latest commits to the test site

[wynnset]

Use Github actions:

• Whenever a new commit is made on a branch
• Build the vue app
• Create a folder for the plugin containing the required files & directories for the plugin (inside of the templates/vue directory, only include the dist directory as other files and directories in there are not used for prod)
• Zip the folder
• Use wp-cli to:
  • Check if there's already a site created for this branch (site name = branch name)
  • If there's no site, create a site and set its permalinks to be post name
  • Upload the new plugin (this needs to be done on the top level of multisite)
  • Activate the plugin on the given site