src: add GetCipherValue function

This commit extracts the code that is the same in GetCipherName,
GetCipherStandardName, and GetCipherVersion into function named
GetCipherValue.

The motivation for this change is to improve readabilty by removing the
duplicated code.

PR-URL: https://github.com/nodejs/node/pull/34287


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>