Resolve #1775
* wip * wip * Refactor * Refactor * wip * wip * wip * wip * Refactor * Refactor * wip * wip * wip * wip * wip * wip * wip * wip * wip * wip * wip * wip * wip * wip * wip * wip * wip * wip * wip * Clean up * Update misskey-flavored-markdown.ts * wip * wip * wip * wip * Update parser.ts * wip * Add new test * wip * Add new test * Add new test * wip * Refactor * Update parse.ts * Refactor * Update parser.ts * wip