Allow scripts to be hidden from lk

[jamescoleuk]

Scenario: someone starts using 'lk' and has loads of scripts in sub-dirs. These scripts have relative paths.

Current outcome: these scripts might fail if run via lk from the project root. Worse, they might cause damage.

Option 1: Add nothing and let people figure this out for themselves/re-write their scripts to be location independent (usually possible).

Option 2: Add some mechanism to allow these scripts to be hidden from lk until they're ported/forever.

I do want to add this feature because it's something that bugs me. Here are some ideas:

1. Add something in the header of these files that lk can detect, e.g.:

#!/usr/bin/env bash
#
# @lk-ignore

2. Add an .lkignore file. But what if lk is run from a sub-dir? It could search the repo-root, if we're in a repo. Otherwise it's less flexible. But it does centralise the ignores. Still, a grep will find them. Or I could add a sub-command to list hidden scripts.