fix(GetUnusedAll): skip non-namespaced resources if --include-namespaces flag is used

[doronkg]

What this PR does / why we need it

Currently, when running kor all -n example, unused non-namespaced resources will be displayed as well.
This PR fixes GetUnusedAll() function to skip non-namespaced resources if --include-namespaces flag is used.
--include-namespaces flag is considered used if the amount of listed namespaces is greater than 0.

In addition, this PR fixes flag typos across the code/docs:

• --include-namespace -> --include-namespaces
• --exclude-namespace -> --exclude-namespaces

PR Checklist

• This PR adds K8s exceptions (false positives)
• This PR adds new code
• This PR includes test for any new code

Github Issue

Resolves #178

Notes for your reviewers

README.md was automatically lintered by IDE, hence newline changes were commited, etc.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 43.45%. Comparing base (333b525) to head (53db71a).
Report is 2 commits behind head on main.

Files	Patch %	Lines
cmd/kor/root.go	0.00%	2 Missing ⚠️
pkg/filters/options.go	0.00%	2 Missing ⚠️
pkg/kor/all.go	0.00%	2 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #258      +/-   ##
==========================================
- Coverage   43.60%   43.45%   -0.15%     
==========================================
  Files          58       58              
  Lines        2768     2775       +7     
==========================================
- Hits         1207     1206       -1     
- Misses       1382     1388       +6     
- Partials      179      181       +2     

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[yonahd]

One comment.
We might want to later also support a flag for including cluster resources but I'm not sure if its needed.

[doronkg]

One comment. We might want to later also support a flag for including cluster resources but I'm not sure if its needed.

We can have a follow-up in a discussion or create a backog issue for that.
Like you, I'm not sure if its needed.

[yonahd]

Lgtm
Thanks