Resource labels support

[grcevski]

This PR extends our resource label support beyond K8s. Currently we were parsing the resource labels only when we see them in k8s metadata, but without k8s we were only setting the name and namespace from the environment variables.

I improved couple of things:

1. Process environment variables have the fully resolved names, therefore we should not clobber them if k8s finds unresolved variables. I allowed this code to run.
2. I ensured we don't store unresolved names in the metadata, so we don't put anything that starts with $.

Co-authored with @skl

[codecov]

Codecov Report

❌ Patch coverage is 89.18919% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 55.14%. Comparing base (30ede70) to head (6b6b85b).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/transform/k8s.go	84.61%	1 Missing and 1 partial ⚠️
pkg/appolly/discover/typer.go	0.00%	0 Missing and 1 partial ⚠️
pkg/kube/store.go	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #907      +/-   ##
==========================================
+ Coverage   45.82%   55.14%   +9.31%     
==========================================
  Files         253      253              
  Lines       26129    21726    -4403     
==========================================
+ Hits        11974    11981       +7     
+ Misses      13331     8921    -4410     
  Partials      824      824              

Flag	Coverage Δ
integration-test	23.25% <16.21%> (+4.26%)	⬆️
integration-test-arm	0.00% <0.00%> (ø)
integration-test-vm-${ARCH}-${KERNEL_VERSION}	0.00% <0.00%> (?)
k8s-integration-test	2.73% <0.00%> (-0.01%)	⬇️
oats-test	0.00% <0.00%> (ø)
unittests	46.26% <83.78%> (+0.01%)	⬆️

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