feat: allow to save cluster + token to kubeconf (#23649)

[adietish]

fixes eclipse-che/che#23649

[codecov-commenter]

Codecov Report

❌ Patch coverage is 65.02591% with 135 lines in your changes missing coverage. Please review.
✅ Project coverage is 27.56%. Comparing base (71098f6) to head (efb2172).
⚠️ Report is 269 commits behind head on main.

Files with missing lines	Patch %	Lines
...ools/gateway/view/steps/DevSpacesServerStepView.kt	0.00%	49 Missing ⚠️
...hat/devtools/gateway/kubeconfig/KubeConfigUtils.kt	73.33%	12 Missing and 16 partials ⚠️
...t/devtools/gateway/kubeconfig/KubeConfigEntries.kt	74.66%	9 Missing and 10 partials ⚠️
...at/devtools/gateway/kubeconfig/KubeConfigUpdate.kt	81.52%	6 Missing and 11 partials ⚠️
...n/com/redhat/devtools/gateway/openshift/Cluster.kt	53.84%	4 Missing and 8 partials ⚠️
.../redhat/devtools/gateway/kubeconfig/FileWatcher.kt	22.22%	7 Missing ⚠️
...vtools/gateway/openshift/OpenShiftClientFactory.kt	0.00%	1 Missing ⚠️
...lin/com/redhat/devtools/gateway/openshift/Utils.kt	91.66%	0 Missing and 1 partial ⚠️
...edhat/devtools/gateway/view/DevSpacesWizardView.kt	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            main     #223       +/-   ##
==========================================
+ Coverage   0.00%   27.56%   +27.56%     
==========================================
  Files          4       38       +34     
  Lines         26     1894     +1868     
  Branches       0      386      +386     
==========================================
+ Hits           0      522      +522     
- Misses        26     1300     +1274     
- Partials       0       72       +72     

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[adietish]

@vrubezhny please review/test. out of the total lines that it adds, 3000 lines are tests 😄

How to test:

Scenario 1:

1. EXEC: get to the server connection wizard page
2. EXEC: provide an url that is not present in the drop down
3. ASSERT: "Save config"-checkbox gets enabled
4. EXEC: check the "Save config"-checkbox
5. EXEC: click "Check connection and continue"

Result:
The connection is validate and you get to the list of available workspaces on your cluster. Then verify that a new context, a new cluster and a new user with the given token are created in either your default kube config file (~/.kube/config) or in the first file listed in KUBECONFIG env var

Scenarion 2:

1. EXEC: get to the server connection wizard page
2. EXEC: provide a new token (token for sandbox expires every 24h)
3. ASSERT: "Save config"-checkbox gets enabled
4. EXEC: check the "Save config"-checkbox
5. EXEC: click "Check connection and continue"

Result:
The connection is validated and you get to the list of available workspaces on your cluster. Then verify that the token in the user referenced in your current context is updated (either it's in your default kube config file at ~/.kube/config or in a file listed in your KUBECONFIG env var).

[adietish]

@vrubezhny: please review, thanks!