Initial commit for the GitHub Action

[dhaus67]

Description

Initial commit for the GitHub Action.

The code is based off of a POC that's been previously done: https://github.com/dhaus67/roxctl-central-login

Besides providing the actual code for the action itself, also creates other meta things like COC, PR templates etc.

What still needs to be done after this:

• Configuring the credentials for rox robot account to allow commiting the dist files.
• Creating another workflow that tests the action by a) spinning up a Central b) configuring the token exchange c) using the action to exchange an access token.

[janisz]

Left some minor comments