Use a script wrapper for <compress>grep

Import the wrapper script from zstdgrep (written by wiz@netbsd.org)

Modify it to support more than just zstd (adding support for gzip,
lzma, xz and bzip2)

Write a simple manpage dedicated for it.

Only use that new wrapper both for gnu grep and bsd grep

Next step will be removing code related to compression format from bsdgrep

Reviewed by: kevans
Approved by: kevans
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D15193