crypto: synchronise with doc

Fixes: https://github.com/nodejs/node/issues/14800

• Improve description of formal args in doc
• Rename formal arguments to match doc
• Merge rsa binding factories

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

crypto,doc