Add TryFrom conversions for Kubeconfig -> Config -> Client

[Danil-Grigorev]

Motivation

This implementation allows kubeconfig to be directly translated into client using try-from implementation.

Previously, user was required to perform a multi-step manipulation to use custom provided kubeconfig without any modification of context or user, which may not be needed if the kubeconfig was constructed as ready to be used, and multiple sources of kubeconfig are used simultaneously.

Solution

Implement TryFrom trate for the Kubeconfig to Client conversion.

let config = Kubeconfig::default();
let cfg = Config::from_custom_kubeconfig(config, &KubeConfigOptions::default()).await?;
let client = Client::try_from(cfg)?;

while new approach is a more straightforward version of this, skipping the configuration step:

let config = Kubeconfig::default();
let client = Client::try_from(config)?;

[codecov]

Codecov Report

❌ Patch coverage is 95.23810% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 76.3%. Comparing base (66083d4) to head (069ccef).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
kube-client/src/config/mod.rs	83.4%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1801     +/-   ##
=======================================
+ Coverage   75.1%   76.3%   +1.2%     
=======================================
  Files         84      84             
  Lines       7792    7899    +107     
=======================================
+ Hits        5851    6024    +173     
+ Misses      1941    1875     -66     

Files with missing lines	Coverage Δ
kube-client/src/client/mod.rs	80.8% <100.0%> (+5.2%)	⬆️
kube-client/src/config/file_loader.rs	77.5% <100.0%> (+2.5%)	⬆️
kube-client/src/config/mod.rs	55.8% <83.4%> (+2.5%)	⬆️

... and 42 files with indirect coverage changes

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[clux]

i think this looks great.

one minor request; you can use it in examples/kubectl to show it off! (it is using the more awkward kubeconfigoptions)

[clux]

this is technically breaking, and we have avoided changing this in the past due to us potentially loading files via tokio::fs.

i guess it is required for the try_from though, so it's probably worth it.

[Danil-Grigorev]

All I could find is #1336, and I think in this instance it is a private method signature change, so it shouldn't be? Since it is not a part of any trait and used only internally? My thought on this was that in case async is needed later, it can be duplicated in a separate method.

[clux]

ah, you are right, this is internal. i'll change it to changelog-add.