l5-mr-fetcher: Add script to Download+Install CI artifact for MRs
The script downloads the latest CI artifact of a specific MR. It tries to guess the correct artifact for the Librem5 or if it can't find one it gives the possibility to manually specify a CI job. Once found a correct artifact it unzips it and installs it.
Based on https://source.puri.sm/snippets/188
Edited by Julian Sparber