many: Snap integrity discovery

[sespiros]

This is based on top of:

• https://github.com/canonical/snapd/pull/14869
• https://github.com/canonical/snapd/pull/14870
• https://github.com/canonical/snapd/pull/14871
• https://github.com/canonical/snapd/pull/14872
• https://github.com/canonical/snapd/pull/15002

and adds a few commits on top which enable snap-bootstrap to use the new APIs in order to mount snaps coming from the seed with dm-verity data.

Jira: https://warthogs.atlassian.net/browse/FR-9883

[codecov[bot]]

Codecov Report

:x: Patch coverage is 78.04878% with 27 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 77.65%. Comparing base (0da3c54) to head (1c13d60). :warning: Report is 238 commits behind head on master.

Files with missing lines	Patch %	Lines
cmd/snap-bootstrap/cmd_initramfs_mounts.go	50.00%	14 Missing and 2 partials :warning:
seed/seed20.go	78.26%	4 Missing and 1 partial :warning:
cmd/snap-bootstrap/initramfs_systemd_mount.go	85.18%	2 Missing and 2 partials :warning:
cmd/snap-bootstrap/cmd_initramfs_mounts_cvm.go	0.00%	0 Missing and 1 partial :warning:
seed/seedtest/seedtest.go	95.45%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #14873      +/-   ##
==========================================
+ Coverage   76.54%   77.65%   +1.10%     
==========================================
  Files        1309     1311       +2     
  Lines      174487   178898    +4411     
  Branches     2307     2332      +25     
==========================================
+ Hits       133563   138916    +5353     
+ Misses      32688    31626    -1062     
- Partials     8236     8356     +120     

Flag	Coverage Δ
unittests	77.65% <78.04%> (+1.10%)	:arrow_up:

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[github-actions[bot]]

Tue Sep 16 16:26:07 UTC 2025 The following results are from: https://github.com/canonical/snapd/actions/runs/17576212263

Failures:

Preparing:

• openstack-ext-ps7:ubuntu-18.04-64:tests/nested/manual/devmode-snaps-can-run-other-snaps
• openstack:opensuse-tumbleweed-selinux-64:tests/main/xdg-open-portal
• openstack:opensuse-tumbleweed-64:tests/main/xdg-open-portal

Executing:

• openstack-ps7:arch-linux-64:tests/main/snap-run
• openstack:opensuse-tumbleweed-selinux-64:tests/main/snapd-snap:lxd
• openstack:opensuse-15.6-64:tests/main/auto-refresh-pre-download:close
• openstack-ps7:ubuntu-25.10-64:tests/main/snap-run
• openstack-ps7:ubuntu-25.10-64:tests/main/interfaces-libvirt
• openstack-ps7:ubuntu-25.10-64:tests/main/snap-network-errors
• openstack-ps7:ubuntu-25.10-64:tests/main/try

Restoring:

• openstack:opensuse-tumbleweed-selinux-64:tests/main/xdg-open-portal
• openstack:opensuse-tumbleweed-64:tests/main/xdg-open-portal

[pedronis]

@alfonsosanchezbeato at this point it seems better to wait to land this after we cut 2.72