Improve code diff rendering styles

[thgaskell]

Problem

Displaying line numbers alongside code diffs was causing alignment issues in the documentation.

Alignment Issue:

Solution

• Updated @docusaurus/* modules to the canary version.
  • This version introduces support for showLineNumbers=N, allowing the starting line number for a code block to be specified.
• Update css to always output the ::before content for every line to ensure every row has same number of "columns".

Light Theme:

Dark Theme:

Default: No line numbers or diffs

[jaygiang]

LGTM ✅