Use user's preferred font for inline code snippets too

Summary:
Use user's preferred font for inline code snippets,
like we already do for block code snippets.

Test Plan:
Set a non-default font in Settings → Display Preferences → Monospaced Font.
Make sure that it applies to both single-tick (inline) and triple-tick (block)
code snippets in comments.

For example, enter:

42px Tahoma

Reviewers: O1 Blessed Committers, valerio.bozzolan

Reviewed By: O1 Blessed Committers, valerio.bozzolan

Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Maniphest Tasks: T15682

Differential Revision: https://we.phorge.it/D25486