add indices in expectation to reserve in-flight indices

[kangclzjc]

What type of PR is this?

Resolve indices conflict issue.

What this PR does / why we need it:

Hostname indices could be re-used however grove doesn't noticed that

Which issue(s) this PR fixes:

Fixes #462

Special notes for your reviewer:

Does this PR introduce a API change?

Add a creationInidices in Expectations

type ControlleeExpectations struct {
	// key is the unique identifier for the resource for which expectations are captured.
	key string
	// uidsToDelete are the set of resource UIDs that are expected to be deleted.
	uidsToDelete sets.Set[types.UID]
	// uidsToAdd are the set of resource UIDs that are expected to be created.
	uidsToAdd sets.Set[types.UID]
	// creationIndices maps UID to the index (e.g. hostname index) assigned to that creation. Optional; only set when
	// ExpectCreations is used so that callers can reserve those indices until the creation is observed.
	creationIndices map[types.UID]int
}

Additional documentation e.g., enhancement proposals, usage docs, etc.: