Add Solargraph configuration

What does this MR do?

Add Solargraph configuration

Adds `.solargraph.yml` to allow `solargraph` to function
for the Ruby files in the codebase.

If `solargraph` is not already installed, run:

`gem install solargraph`

or

`bundle install`

At this time, the supported editors include:
- Visual Studio Code
- Atom
- Sublime Text
- Eclipse
- Vim
- Emacs

Source: https://solargraph.org

Testing

1. Run bundle install, confirming solargraph is installed.
2. Open one of the supported editors.
3. Install/configure the Solargraph plugin for your editor (more info at Solargraph).
4. Open one of the Ruby files.
5. Ensure the LSP functionality works as expected.

Screenshots

Function helper

Definition popup

Go to definition/reference

Would need a gif rather than a screenshot, but effectively this enables the ability to jump to an object's definition as well as see a list of everywhere that object is referenced.

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• When ready for review, MR is labeled "~workflow::ready for review" per the Distribution MR workflow

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened
• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file.