[FLORA-62] Search executable by name

[tchoutri]

Proposed changes

This PR introduces the exe: search modifier, which brings up the packages with exact or very similar names.

Contributor checklist

• [x] My PR is related to FLORA-62
• [x] I have read and understood the CONTRIBUTING guide
• [x] I have inserted my change and a link to this PR in the CHANGELOG

[tchoutri]

@geekosaur What do you think?