Add hover documentation for reserved keywords

[mikeygough]

Partially closes #2227

This PR adds hover documentation for the following Ruby reserved keywords:

• break
• case
• class
• def
• defined?
• else
• ensure
• for
• module
• next
• rescue
• return
• undef
• unless
• until
• when
• while

ruby-keyword-hover-documentation-demo.mov

This documentation was written by AI following Shopify's Ruby style guide. It has been reviewed by myself but would appreciate additional, more experienced eyes!

NOTE - The following keywords still need definitions which may require modifying their associated Prism Node:

• alias
• and
• begin
• do
• elsif
• end
• false
• if
• in
• nill
• not
• or
• redo
• retry
• self
• super
• then
• true

Motivation

We can deliver a better Ruby programming experience if developers can hover over built-in keywords to learn more about how they work!

Implementation

This implementation follows a pattern established by the yield keyword. It adds a key value pair to the KEYWORD_DOCS' hash inside static_docs.rb, writes a keyword specific markdown file that goes into a deeper explanation and extends hover.rb` to handle keyword specific hover events.

Automated Tests

Run dev t

Manual Tests

Start the Ruby LSP. Use some keywords and checkout the tooltips + related documentation!

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