Support specifying the transfer net by configmap

[mansam]

The k8s.v1.cni.cncf.org/networks annotation supports a json value with a list of NetworkSelectionElements that contain additional configuration for the secondary network attachment, including a default route.

This change allows the user to specify the transfer network by referencing a ConfigMap that contains a NetworkSelectionElement. The Plan CR already uses an ObjectReference type for the transferNetwork field, so we can take advantage of the kind field on the ObjectReference to specify that a ConfigMap is being used without having to make any changes to the Plan CR. The transfer network validation has been expanded to check that the ConfigMap is in the correct format and that the NAD the ConfigMap refers to exists.

To maintain compatibility with previous versions of Forklift, the original behavior (using the v1.multus-cni.io/default-network annotation) is preserved if a ConfigMap is not specified in the Plan.

kind: ConfigMap
apiVersion: v1
metadata:
  name: secondary-net-config
  namespace: default
data:
  interface: net2
  name: secondary-net
  namespace: default
  default-route: [...]

spec:
  targetNamespace: default
  transferNetwork:
    kind: ConfigMap
    name: secondary-net-config
    namespace: default
  vms:
    - id: vm-1074
      name: slucidi-mtv

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 106 lines in your changes missing coverage. Please review.

Project coverage is 15.55%. Comparing base (fb5b40e) to head (f92be76).

Files with missing lines	Patch %	Lines
pkg/controller/plan/validation.go	0.00%	66 Missing ⚠️
pkg/controller/plan/kubevirt.go	0.00%	40 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1241      +/-   ##
==========================================
- Coverage   15.62%   15.55%   -0.07%     
==========================================
  Files         112      112              
  Lines       23123    23215      +92     
==========================================
  Hits         3612     3612              
- Misses      19226    19318      +92     
  Partials      285      285              

Flag	Coverage Δ
unittests	15.55% <0.00%> (-0.07%)	⬇️

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[mansam]

Superceded by #1244