Allow ChildReconciler to opt-in to dangerous children

[scothis]

Duck types represent a partial view of a resource. It is dangerous to perform operation that assume the client has the full resource when it only has a portion of the resource. Calling update in this case can result in data loss as fields that are not part of the duck type will be dropped on the server. Likewise, it is difficult to create a resource with a partial object as required/essential fields may not be available.

This change allows users to explicitly override these concerns and use the ChildReconciler and ChildSetReconciler to manage a child via a duck type. This should only be done when the user is certain the duck typed object contains all fields represented on the resource.

[codecov[bot]]

Codecov Report

Attention: 16 lines in your changes are missing coverage. Please review.

Comparison is base (e22ffba) 60.67% compared to head (ce3c333) 60.43%.

Files	Patch %	Lines
reconcilers/child.go	23.07%	9 Missing and 1 partial :warning:
reconcilers/config.go	0.00%	6 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #455 +/- ## ========================================== - Coverage 60.67% 60.43% -0.24% ========================================== Files 26 26 Lines 2543 2563 +20 ========================================== + Hits 1543 1549 +6 - Misses 911 924 +13 - Partials 89 90 +1 ```

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[squeedee]

Still want to review this, just so you know, we haven't forgotten it :D

[squeedee]

I'm leaving this pending until I have time to evaluate it with something real world. I like this solution a lot, for my very specific usecase, but adding something dangerous only to satisfy my use case might be selfish.

[scothis]

Migrated to https://github.com/reconcilerio/runtime/pull/506