request: warn on simple infinite recursion

[mcandre]

For new checks and feature suggestions

• https://www.shellcheck.net/ (i.e. the latest commit) currently gives no useful warnings about this
• I searched through https://github.com/koalaman/shellcheck/issues and didn't find anything related

Here's a snippet or screenshot that shows the problem:

#!/bin/sh
$0

or

#!/bin/sh
exec $0

Here's what shellcheck currently says:

N/A

Here's what I wanted or expected to see:

Warning: Risk of infinite recursion. Supply at least one CLI argument to the command $0.