feat: add new metadata to stack

[katcipis]

Add new metadata:

• terramate.stack.path.relative
• terramate.stack.path.basename
• terramate.stack.path.to_root

[codecov]

Codecov Report

Merging #383 (738757c) into main (3ba85b2) will decrease coverage by 0.05%.
The diff coverage is 62.50%.

@@            Coverage Diff             @@
##             main     #383      +/-   ##
==========================================
- Coverage   69.43%   69.37%   -0.06%     
==========================================
  Files          37       37              
  Lines        7318     7335      +17     
==========================================
+ Hits         5081     5089       +8     
- Misses       1977     1985       +8     
- Partials      260      261       +1     

Flag	Coverage Δ
tests	69.37% <62.50%> (-0.06%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
cmd/terramate/cli/cli.go	5.52% <0.00%> (-0.02%)	⬇️
stack/stack.go	62.06% <66.66%> (-2.41%)	⬇️
stack/eval.go	74.13% <100.00%> (+1.41%)	⬆️

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[i4ki]

lgtm