Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

Move all sh and csh files into bin/sh/ or bin/csh/

This simplifies pkgbase by migrating these to CONFS so they are properly
tagged as config files.

Approved by: will (mentor)
Differential Revision: https://reviews.freebsd.org/D16708