Update Go (build/test) version to 1.23

[0x0013]

We are seeing errors in GH action tests, such as:

go.mod:3: invalid go version '1.23.0': must match format 1.23

This is due to older versions of Go not supporting X.Y.Z versioning, and prevents any changes due to failing CI.

To resolve this, update the Go version used by GH actions to the latest stable 1.23.3. For consistency, also update the version used for build in Dockerfile and asdf .tool-versions.

Some downstream changes were also done because of this:

• pin envtest as per Fix Kustomize deprecations #335 - however, use newer version since we're updating Go
• update controller-gen to 0.14 - see Controller-gen panic when using go 1.22 kubernetes-sigs/controller-tools#880
• update CRD manifests generated by controller-gen (seems they are only stylistic changes with no change in behavior)

New release should not be needed since this is a non-functional change.