feat: support option parsing for grep -C flag

[nfischer]

This adds support for shelljs/shelljs#1206. This requires special parsing logic on the shx side.

Test: npm test
Test: ./lib/cli.js grep -A 1 'foo' ~/foobartest.txt
Test: cat ~/foobartest.txt | ./lib/cli.js grep -A 1 'foo'

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (241e1ff) to head (68bd9db).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #236   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          116       122    +6     
=========================================
+ Hits           116       122    +6     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.