feat: support separator in select prompt

[zonemeen]

Initial solution on #1230

If this solution works, I will add it to the rest of the prompts.

[codecov]

Codecov Report

Patch coverage: 73.91% and project coverage change: -0.04 ⚠️

Comparison is base (f3bfe3b) 78.76% compared to head (9425cb0) 78.73%.

❗ Current head 9425cb0 differs from pull request most recent head f573276. Consider uploading reports for the commit f573276 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1231      +/-   ##
==========================================
- Coverage   78.76%   78.73%   -0.04%     
==========================================
  Files          34       35       +1     
  Lines        3575     3598      +23     
  Branches      576      578       +2     
==========================================
+ Hits         2816     2833      +17     
- Misses        187      192       +5     
- Partials      572      573       +1     

Impacted Files	Coverage Δ
packages/core/src/lib/Separator.mts	64.70% <64.70%> (ø)
packages/core/src/index.mts	79.18% <100.00%> (+0.65%)	⬆️

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[SBoudrias]

I went ahead addressing my PR comments. Hoping to get this in today!

Thanks for sending the PR and doing most of the work, it definitively helped!

[zonemeen]

Nice work! I'm also happy to be involved in boosting Inquirer.js.