Slack Notification UI - Incorrect Text Formatting

### Environment SaaS (https://sentry.io/) ### Steps to Reproduce 1. Generate a Slack alert where the title contains reserved Slack characters such as `: wave :` (with no spaces between the :). Notice that the title now contains the emoji for the wave instead of the actual word. 2. Generate a Slack alert where the title contains the reserved Slack characters for code formatting with backtick character `. Observe the title now is partially formatted as code instead of as a hyperlink. 3. Generate a Slack alert where the tag is at maximum character limit. Observe that the Slack formatting for that tag is in regular text instead of formatted as code. ### Expected Result As a user, it would be great to have an option to toggle markdown for Slack alert notifications. For the most part, I'd only want markdown on the Notes field and not on any of the other fields. ### Actual Result  ### Product Area Issues ### Link _No response_ ### DSN _No response_ ### Version _No response_