Add helper for creating a controller owner_ref on Resource

[clux]

Motivation

Controllers frequently have to create owned objects with owner references pointing back to the object we get passed to reconcile.

We would like a way to quickly populate the OwnerReference struct for this case to avoid having to hand-cook this in every controller.

Solution

Grab the function in configmapgen_controller and add it as a Resource::controller_owner_ref impl.

It's possible we should put this elsewhere, am open to ideas, but we should have something like this.

[codecov-commenter]

Codecov Report

Merging #850 (da52814) into master (47fcf10) will decrease coverage by 0.12%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master     #850      +/-   ##
==========================================
- Coverage   70.42%   70.29%   -0.13%     
==========================================
  Files          59       59              
  Lines        4203     4212       +9     
==========================================
+ Hits         2960     2961       +1     
- Misses       1243     1251       +8     

Impacted Files	Coverage Δ
kube-core/src/resource.rs	51.35% <0.00%> (-7.12%)	⬇️
kube-runtime/src/wait.rs	70.00% <0.00%> (+2.00%)	⬆️

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