PLAN B: Add "Ruby" as new required ecosystem choice to sit beside "RubyGems" ecosystem

[jasnow]

PLAN B: Add "Ruby" as new required ecosystem choice to sit beside "RubyGems" ecosystem

If PR#1796 is too much of a change to do ALL-AT-ONCE, then I suggest adding Ruby as new required ecosystem choice to sit beside "RubyGems" ecosystem**

This definition of the new "Ruby" ecosystem would be yes ruby but not RubyGem (not on RubyGems).

The reasons are the same as PR#1796 but would be incremental.

PR#1796's Reasons to do this:
   * Most of the other ecosystem choices are the language name.
 * Deal with the existing "non-reviewed" ruby-related advisories which have no value to be assigned.
This will help the GHSA staff to work some of the 142 "unreviewed" ruby advisories.

Query: type:unreviewed 'ruby'"
Here is the current list ruby-lang vulnerabilities: ruby-lang Security

I work on the https://github.com/rubysec/ruby-advisory-db project.

CC: @taladrane