feat: Add native image handler backend

[project0]

This change adds a new native backend to remove eventually the need to depend on external skopeo binary. Using the native library allows much better control and error handling. It also enables us to add more easily new features like signing for example.

• Migrate image inspect and copy into a interface
• Migrate skopeo based calls into new package
• Remove code duplication in registries
• Add cache layer backend
• Add new optional alternative native image backend

implements #443

[project0]

~I had no time to test it yet :-)~ edit: works like a charm ;-)

[project0]

It might need extra build tags to fix the gpgme dependency: https://github.com/containers/image#supported-build-tags

[codecov[bot]]

Codecov Report

Patch coverage: 2.29% and project coverage change: +2.81 :tada:

Comparison is base (123ee5b) 34.08% compared to head (2490389) 36.89%.

:exclamation: Current head 2490389 differs from pull request most recent head 94937fa. Consider uploading reports for the commit 94937fa to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #497      +/-   ##
==========================================
+ Coverage   34.08%   36.89%   +2.81%     
==========================================
  Files           9       10       +1     
  Lines         848      786      -62     
==========================================
+ Hits          289      290       +1     
+ Misses        534      471      -63     
  Partials       25       25              

Impacted Files	Coverage Δ
pkg/config/config.go	0.00% <ø> (ø)
pkg/registry/cache.go	0.00% <0.00%> (ø)
pkg/registry/client.go	25.58% <0.00%> (-12.35%)	:arrow_down:
pkg/registry/gar.go	13.59% <5.26%> (+4.67%)	:arrow_up:
pkg/registry/ecr.go	8.79% <6.66%> (+2.54%)	:arrow_up:

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[mloiseleur]

Hello @estahn,

Wdyt of this PR ? Anything needed ?

[estahn]

@project0 Apologies it took me so long to look at things. Could you resolve the conflicting files? I tried, but there are some changes in ecr.go I'm not entirely sure about.