[Feature]: Add default inline code blocks

[KonnorRogers]

Inline code blocks are currently supported out of the box by TipTap / Rhino Editor, however they have no default styles, and it has a few bugs like when the inline code is at the start of a line that are solved by this ProseMirror extension:

https://discuss.prosemirror.net/t/new-plugin-prosemirror-codemark-to-handle-inline-code-mark-creation-and-manipulation/4159

I'll see how easy it is to upstream fixes to TipTap, if not, fallback to the ProseMirror plugin.

Feature inspired by:

basecamp/trix#1195