fix: update coding challenges page

[jdwilkin4]

This PR does the following

• cleans up the introductory text and removes the outdated references
• adds a section for the breakdown of the core curriculum and links to the specialized guides like workshops and labs
• removes the how to work on workshops section since that information was presented in the previous section
• updates the template to remove outdated information and removes information only needed for language curricula(there is a separate guide for that)
• moves the numbering challenges section to the video challenges page since that is where it is needed
• removes naming challenges section completely because that is no longer needed with this version of the curriculum
• updates the seed code comments section with more recent examples from workshops
• removes sections marked as deprecated
• removes old video for testing challenges
• adds a section for creating projects

Checklist:

• I have read freeCodeCamp's contribution guidelines.
• My pull request has a descriptive title (not a vague title like Update index.md)

Closes #1228
closes #1229

[majestic-owl448]

you can use the *-challenge scripts, now that they are updated they work with generating files that have the usual id.md naming pattern, freeCodeCamp/freeCodeCamp#66354

if needed the template they use can be updated more