Build from snapcraft.yaml and use ucdev PPA

[alfonsosanchezbeato]

Remove makefile and do special steps from an override-build section instead.

Take now signed grub and shim form the ucdev/uc-staging-ppa PPA, using package-repositories. Now we use epochs in the version of grub-efi-amd64-signed and shim-signed packages, so the build should always take the ones from the PPA instead of those in the archive, as 2:<version> will always be greater than the package version in the latter. Nonetheless, do an additional static check for this.

Forward-ported from https://github.com/snapcore/pc-amd64-gadget/pull/65

[alfonsosanchezbeato]

Note that this will not build until we have jammy binaries in https://launchpad.net/~ucdev/+archive/ubuntu/uc-staging-ppa.

[vorlonofportland]

Note that this will not build until we have jammy binaries in https://launchpad.net/~ucdev/+archive/ubuntu/uc-staging-ppa.

Those binaries are there as of yesterday..

[alfonsosanchezbeato]

Note that this will not build until we have jammy binaries in https://launchpad.net/~ucdev/+archive/ubuntu/uc-staging-ppa.

Those binaries are there as of yesterday..

For focal... not for jammy. For jammy we have a good shim in the old PPA, I would like to upload a new one when we have shim 15.6 signed by Microsoft.

[alfonsosanchezbeato]

Now that we have the jammy packages, I've rebased this PR.

[alfonsosanchezbeato]

Somewhat gadgets built using shim/grub from latest in ucdev are failing for FDE, blocking the merge for the moment.

[alfonsosanchezbeato]

Needs fixing in light of #81 getting merged

Rebased now

[alfonsosanchezbeato]

Updated by adding "assumes" cc @xnox