Escape CEL Reserved Keywords when Generating Validation Rules

[dalton-hill-0]

Description of your changes

Fixes #254

Wraps CEL reserved keywords found in Validation Rules (i.e., __{keyword}__).

For instance, if the object has a field "namespace", this would be the before and after in zz_<obj>_types.go

- // +kubebuilder:validation:XValidation:rule="self.managementPolicy == 'ObserveOnly' || has(self.forProvider.namespace)",message="namespace is a required parameter"
+ // +kubebuilder:validation:XValidation:rule="self.managementPolicy == 'ObserveOnly' || has(self.forProvider.__namespace__)",message="namespace is a required parameter"

The same diff, for the generated CRD

            x-kubernetes-validations:
            - message: namespace is a required parameter
-             rule: self.managementPolicy == 'ObserveOnly' || has(self.forProvider.namespace)
+             rule: self.managementPolicy == 'ObserveOnly' || has(self.forProvider.__namespace__)

I have:

• Read and followed Crossplane's contribution process.
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR if necessary.

How has this code been tested

• Updated existing unit tests to include Validation Rules.
• Manually wrapped code in generated CRDs to ensure the escaping actually resolves the issue.

[Upbound-CLA]

All committers have signed the CLA.

[dalton-hill-0]

PR is ready for review
@ulucinar @sergenyalcin

[lsviben]

Minor comment, otherwise LGTM. Thanks @dalton-hill-0 for the contribution!

[ulucinar]

nit:

Suggested change

	func sanitizePath(p string) string {
	func escapeName(p string) string {

[ulucinar]

nit: We may use a map[string]struct{} (or the higher-level "k8s.io/apimachinery/pkg/util/sets.Set ) for O(1) lookups. Also the list we search has a relatively static small size.