Volcano admission: Validate that ExactMatch or RegexMatch field not null when MemberSelectorType matches

[Monokaix]

Part implementation of #3850

MemberSelector field of hyperNode crd:
type MemberSelector struct {
	// Type specifies the selection method (Exact or Regex).
	// +kubebuilder:validation:Enum=Exact;Regex
	// // +required
	Type MemberSelectorType `json:"type"`

	// ExactMatch defines the exact match criteria (required when Type is "Exact").
	// +optional
	ExactMatch *ExactMatch `json:"exactMatch,omitempty"`

	// RegexMatch defines the regex match criteria (required when Type is "Regex").
	// +optional
	RegexMatch *RegexMatch `json:"regexMatch,omitempty"`
}

When MemberSelectorType is set to Exact, should check that ExactMatch is not null, when MemberSelectorType is set to Regex, should check that RegexMatch is not null.

[Xu-Wentao]

/assign

[Monokaix]

/kind feature

[JesseStutler]

@Xu-Wentao
I have a new admission requirement here: node label volcano.sh/hypernodes validation:

1. The format of the label must be "hypernode-0,hypernode-1,...,hypernode-n", use commas to separate different hypernodes, hypernode name cannot be empty, such as "hypernode-0,,,,", the name of hypernode must be legal.
2. only the hypernode of tier 1 is allowed to be changed, such as s0,s4,s6 can be updated to s1,s4,s6, but the hypernode of tier > 1 is not allowed to be changed, such as s0,s4,s6 changed to s0,s5,s6. It is also not allowed to increase or decrease the length. For example,s0,s4,s6 cannot be updated to s0,s4 or s0,s4,s6,s7. However, it is allowed to delete the label or set the value to an empty string.

[JesseStutler]

@Monokaix May need to rewrite the description of this issue and separate ExactMatch or RegexMatch validation and node label volcano.sh/hypernodes as two tasks in it.