[native] Move useTextMessageMarkdownRules to message-list-types.js

Summary: I want to use this function in another place, so we can generate and cache the Markdown AST upstream of InnerTextMessage in order to determine whether the Markdown includes a "pressable" (link or spoiler for now, but @mention in the future).

Test Plan: Flow

Reviewers: rohan, atul, ginsu, michal

Reviewed By: rohan

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D5753