Entry API

[nightkr]

Motivation

Fixes #810

Solution

Introduces a new method Api::entry, analogous to std's HashMap::entry, allowing for a (hopefully) ergonomic API for get-and-create and get-and-modify use cases.

The API should be similar to HashMap::entry, but adds an explicit Entry::sync() method for writing back any changes to K8s, allowing the user to control how and when batching happens.

[clux]

very clean in general, left one minor nit, but also a more future oriented problem with using replace

[codecov-commenter]

Codecov Report

Merging #811 (3c20ff5) into master (cbf5f91) will decrease coverage by 0.11%.
The diff coverage is 72.15%.

@@            Coverage Diff             @@
##           master     #811      +/-   ##
==========================================
- Coverage   70.08%   69.96%   -0.12%     
==========================================
  Files          58       59       +1     
  Lines        3984     4145     +161     
==========================================
+ Hits         2792     2900     +108     
- Misses       1192     1245      +53     

Impacted Files	Coverage Δ
kube-client/src/api/mod.rs	57.14% <42.10%> (-29.53%)	⬇️
kube-client/src/api/entry.rs	75.79% <75.79%> (ø)
kube-client/src/config/mod.rs	50.00% <0.00%> (-7.15%)	⬇️
kube-client/src/client/mod.rs	70.25% <0.00%> (ø)
kube-client/src/api/core_methods.rs	86.66% <0.00%> (+2.22%)	⬆️

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[clux]

This is looking very professional, had a good go over now and could only find a few nits on documentation. The integration tests are very good (i see the coverage has bounced back from the earlier pr state 👍), and presumably these are pretty fast since it's just configmap mutations.

some unknowns on the potential error cases where people manually set metadata.{name,namespace,generate_name} but there's already a thread for it

[clux]

had a quick look at the generated docs, looks great!

ah, actually, we still have some error cases to decide on

[clux]

looks very clean now, no other comments on this.
merge away at your leisure, and please open up any follow-up enhancement issue ideas (like the filthyref idea)