[EPIC] Setup Docs Refactor

[matejminar]

Problem:

The current experience to add, fetch and render our onboarding docs is very painful because:

1. It is not easy to see your changes in your local dev environment
2. To see your changes in production, sentry-docs has to be released
3. We have hacky CSS to make everything look like Sentry style
4. If you need to create a document in a format that does not match the defined pattern, the build won’t pass, forcing you to manually update functions in sentry-docs as well as the sentry repository.
   These updates are usually conditional on a case-by-case basis and the list can grow very large and this is not scalable.
5. To provide a dynamic code snippet experience it is necessary to replicate the same document in the docs. See Onboarding wizard for errors + replay + performance sentry-docs#6633

Proposed solution:

At our last 2x Frontend TSC meetings we discussed the RFC “Move Docs to Sentry Repository”, coming to the conclusion that we would just like to move the quick start docs to our sentry repository, where we will either continue to use MDX files or just use our own React components

Expected outcome:

• Transition the onboarding documentation (quick-start) from the sentry-docs repository to the main sentry repository, starting with JavaScript platforms.
• Implement a simple and user-friendly structure that is easy for non-developers to work with (create/update) and understand.
• Ensure that the documentation is properly rendered in all onboarding entry points, including in the onboarding for new organizations, and create project UI.
• Create a guide for creating and updating onboarding documents in the sentry repository.

Useful Link:
https://github.com/getsentry/rfcs/blob/main/text/0084-move-docs-to-sentry-repository.md

Notion Doc: https://www.notion.so/sentry/Setup-docs-refactor-01ed795a111d43569e3ccebe9def4989

### PoC
- [ ] https://github.com/getsentry/sentry/issues/47470
- [ ] https://github.com/getsentry/sentry/issues/49934

### Gradually migrate "Getting Started" documentation from sentry-docs to sentry's main repository
- [ ] https://github.com/getsentry/sentry/issues/52121
- [ ] https://github.com/getsentry/sentry/issues/52133
- [ ] https://github.com/getsentry/sentry/issues/52137
- [ ] https://github.com/getsentry/sentry/issues/52138
- [ ] https://github.com/getsentry/sentry/issues/52139
- [ ] https://github.com/getsentry/sentry/issues/52140
- [ ] https://github.com/getsentry/sentry/issues/52141
- [ ] https://github.com/getsentry/sentry/issues/52142
- [ ] https://github.com/getsentry/sentry/issues/52155
- [ ] https://github.com/getsentry/sentry/issues/52156
- [ ] https://github.com/getsentry/sentry/issues/52157
- [ ] https://github.com/getsentry/sentry/issues/52154
- [ ] https://github.com/getsentry/sentry/issues/52122
- [ ] https://github.com/getsentry/sentry/issues/52153
- [ ] https://github.com/getsentry/sentry/issues/52152
- [ ] https://github.com/getsentry/sentry/issues/52151
- [ ] https://github.com/getsentry/sentry/issues/52150
- [ ] https://github.com/getsentry/sentry/issues/52149
- [ ] https://github.com/getsentry/sentry/issues/52148
- [ ] https://github.com/getsentry/sentry/issues/52147
- [ ] https://github.com/getsentry/sentry/issues/52146
- [ ] https://github.com/getsentry/sentry/issues/52145
- [ ] https://github.com/getsentry/sentry/issues/52143
- [ ] https://github.com/getsentry/sentry/issues/52144