feat: registry proxy tls support

[AustinAbro321]

Description

This adds mtls support to the registry proxy solution.

When registry proxy is used the client will check the CA cert from the server. It won't recognize it and it will error out on operations unless the transport is configured to recognize the CA cert. This will be done automatically when registry proxy is used. Older versions of Zarf will not be able to push to the registry unless --insecure-skip-tls-verify is used. This is expected and okay especially since we're starting with this in alpha and if someone runs zarf init --registry-proxy then the new version of Zarf is already available in their airgap environment.

Checklist before merging

• Test, docs, adr added or updated as needed
• Contributor Guide Steps followed

[codecov]

Codecov Report

❌ Patch coverage is 19.33086% with 217 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/pkg/cluster/cluster.go	0.00%	112 Missing and 1 partial ⚠️
src/pkg/pki/pki.go	42.01%	63 Missing and 6 partials ⚠️
src/internal/packager/images/push.go	5.40%	33 Missing and 2 partials ⚠️

Files with missing lines	Coverage Δ
src/internal/packager/images/push.go	44.49% <5.40%> (-7.55%)	⬇️
src/pkg/pki/pki.go	47.08% <42.01%> (-15.73%)	⬇️
src/pkg/cluster/cluster.go	31.36% <0.00%> (-12.85%)	⬇️

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