basic xonsh support

[synfinatic]

Support eval/exec commands.

Refs: #1018

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 9 lines in your changes missing coverage. Please review.

Project coverage is 51.11%. Comparing base (4d84ccc) to head (5477abc).
Report is 2 commits behind head on main.

Files	Patch %	Lines
cmd/aws-sso/exec_cmd.go	0.00%	5 Missing ⚠️
cmd/aws-sso/eval_cmd.go	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1033      +/-   ##
==========================================
- Coverage   51.18%   51.11%   -0.07%     
==========================================
  Files          60       60              
  Lines        4994     5001       +7     
==========================================
  Hits         2556     2556              
- Misses       2345     2352       +7     
  Partials       93       93              

Flag	Coverage Δ
unittests	51.11% <0.00%> (-0.07%)	⬇️

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Files	Coverage Δ
cmd/aws-sso/eval_cmd.go	0.00% <0.00%> (ø)
cmd/aws-sso/exec_cmd.go	0.00% <0.00%> (ø)

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