Make snow validator an interface

[vivek-koppuru]

Issue #, if available:

Description of changes: Continuation of addressing comments from https://github.com/aws/eks-anywhere/pull/2724 and https://github.com/aws/eks-anywhere/pull/2817 for the snow machine config controller work.

Specifically addressing https://github.com/aws/eks-anywhere/pull/2724#discussion_r931324391

Testing (if applicable): unit test

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[codecov[bot]]

Codecov Report

Merging #2887 (e035f52) into main (af52724) will increase coverage by 0.09%. The diff coverage is 92.77%.

@@            Coverage Diff             @@
##             main    #2887      +/-   ##
==========================================
+ Coverage   62.15%   62.24%   +0.09%     
==========================================
  Files         333      334       +1     
  Lines       26816    26849      +33     
==========================================
+ Hits        16667    16713      +46     
+ Misses       8868     8854      -14     
- Partials     1281     1282       +1     

Impacted Files	Coverage Δ
pkg/dependencies/factory.go	67.87% <0.00%> (ø)
controllers/factory.go	93.33% <100.00%> (+0.04%)	:arrow_up:
controllers/snow_machineconfig_controller.go	89.83% <100.00%> (-0.80%)	:arrow_down:
pkg/aws/snow.go	67.85% <100.00%> (-1.11%)	:arrow_down:
pkg/providers/snow/clientregistry.go	100.00% <100.00%> (ø)
pkg/providers/snow/defaults.go	79.48% <100.00%> (+10.47%)	:arrow_up:
pkg/providers/snow/entry.go	56.09% <100.00%> (ø)
pkg/providers/snow/reconciler/clientbuilder.go	90.47% <100.00%> (+0.82%)	:arrow_up:
pkg/providers/snow/validator.go	100.00% <100.00%> (+17.50%)	:arrow_up:
pkg/curatedpackages/bundle.go	67.44% <0.00%> (-5.40%)	:arrow_down:
... and 3 more

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[vivek-koppuru]

/approve

[eks-distro-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: vivek-koppuru

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[vivek-koppuru]

/hold

[vivek-koppuru]

/unhold