[Replicant] vendor_replicant-scripts: Add Replicant 11 support to add_adb_root

[Denis 'GNUtoo' Carikli]

Hi,

As promised in the previous patchset, here's the next part.

It cleanups a lot the code and also adds support for bootimages
with an initramfs compressed with xz.

So far there is no automatic test for Replicant 11 so the test was
made manually.

Automatic tests for it could be added later on when we will have
some official test images (like alpha images).

In addition to the patches that will follow in a response to
this mail, here's an URL to the see the patches in a web interface:
https://git.replicant.us/contrib/GNUtoo/vendor_replicant-scripts/commit/?id=9da920b9c8464ca953aed1de2cbf838acfbb0825

And here's how to get them in a git repository:
git clone https://git.replicant.us/GNUtoo/vendor_replicant-scripts
cd vendor_replicant-scripts
git show 9da920b9c8464ca953aed1de2cbf838acfbb0825

Denis.