Refresh Guide tab content

[pkalita-lbl]

Fixes #199

Summary

The main purpose of these changes is to update the content of the Guide tab in accordance with various team member contributions (see the Guide Tab Content doc in the squad folder). While moving content from the Google doc into the codebase I took the opportunity to streamline how we incorporate Markdown content in the app.

Details

• Currently different sections of the Guide tab have their content stored in separate .md.ts files, which are TypeScript files, but they export string variables that hold Markdown content. I found that a little cumbersome and also a bit restrictive. With these changes, all the Markdown-based content for the Guide tab is stored in one plain Markdown file (src/pages/GuidePage/md/guide-page.md).
• I added a new component to render Markdown text (src/components/Markdown/Markdown.tsx) which mainly just renders # Level 1 Headings with the SectionHeader component. It also adds a very minimal bit of styling to other elements. Unlike the current Checklist component, this does not attempt to render Markdown bulleted lists as IonLists. With these changes, the Guide content became quite a bit more text-heavy, and the IonLists didn't seem to suit it as well anymore.
• I'm using Vite's static asset handling functionality to load the Markdown content by using the ?raw suffix.
• The orphaned Checklist page has been removed, and all remaining pages/components uses the "Guide" nomenclature.

[eecavanna]

Thank you for implementing this, including refactoring the way the Markdown content was stored and soliciting content feedback from team members. LGTM!