Developer scripts: Release script

Developer scripts: Release script

The old release script that exists in another repository has aged, and
risks becoming messy beyond maintainability if it's made to deal with
multiple OpenSSL version schemes.

A solution, which has been seen in other projects, is to have the
release script as part of the versioned source tree, and ensure it's
adapted for the ongoing version scheme in that source tree.

This introduces dev/, a directory of OpenSSL developer "stuff".  We
may expand it with other practical scripts to easy development setup
and other similar things that developers may need.  For now, it's the
release script dev/release.sh, with auxilliary files in dev/release-aux/.
The script is self describing, the manual is available by running the
command `./dev/release.sh --manual`.

The dev/ directory shall never appear in a source distribution.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11516)