REPL: Show input alias (e.g., \\:cat:) for Char display (#58181)
This PR enhances the REPL display for Char types.
It adds the LaTeX/emoji input alias after the standard Unicode
information, making it consistent with the help?> mode behavior.
For example, `'😼'` will now display as:
`'😼': Unicode U+1F63C (category So: Symbol, other), input as
\:smirk_cat:`
**(Self-contained paragraph explaining the choice):**
Considered modifying `Base.show` directly, but opted for adding a
`REPL.show_repl` method instead to avoid introducing a dependency from
`Base` on the `REPL` module's symbol mapping (`symbol_latex`). This
approach keeps the REPL-specific display logic contained within the REPL
module.
Closes #58158
