feat: support inline auth

[arturshadnik]

Issue

Resolves #139

Description

• Moved apiToken into the Auth struct. A CRD can now be applied with either a reference to a secret OR an API Token.
• Simplified Validate() function signature, since all required info is now in the Spec, which can be passed in either from the controller or or from validatorctl in direct mode.
• Added a sample CRD showing using inline auth
• Went back to using canonical/gomaasclient since a new release was published with the changes we needed.

[codecov]

Codecov Report

Attention: Patch coverage is 44.44444% with 5 lines in your changes missing coverage. Please review.

Files	Patch %	Lines
internal/controller/maasvalidator_controller.go	28.57%	3 Missing and 2 partials ⚠️

@@            Coverage Diff             @@
##             main     #142      +/-   ##
==========================================
- Coverage   74.22%   71.10%   -3.13%     
==========================================
  Files           9        9              
  Lines         357      353       -4     
==========================================
- Hits          265      251      -14     
- Misses         76       85       +9     
- Partials       16       17       +1     

Files	Coverage Δ
api/v1alpha1/maasvalidator_types.go	76.92% <ø> (ø)
pkg/validate/validate.go	75.60% <100.00%> (ø)
internal/controller/maasvalidator_controller.go	45.83% <28.57%> (-23.40%)	⬇️

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