[epic] edx-platform XBlock Extraction

[feanil]

In this epic we will extract out all the xblocks exists in edx-platform here

We have created a new repo where all these xblocks will reside sharing the common requirements file and release process.

Here is the core architecture PR for this repo

More details here: https://openedx.atlassian.net/wiki/spaces/AC/pages/4243030019/edx-platform+XBlock+extraction

Rationale

• The extracted blocks will need to use the pure XBlock API rather than by cheating with edx-platform's remnant XModule-esque APIs. This will force us to improve several aspects of the XBlock API which are currently lacking for custom XBlocks.
• We need to remove XBlock frontends from edx-platform in order to complete the MFE conversion process and remove edx-platform's outdated, hard-to-maintain legacy frontend tooling.
• This will help simplify the relationship between LMS and CMS.
• The extracted blocks will be easier to maintain and test in isolation.
• We are fixing bugs and generating documentation along the way.

[irtazaakram]

We will now move these xblocks to single repo as discussed here openedx/axim-engineering#1169

Repo: https://github.com/openedx/xblocks-contrib

[nsprenkle]

I'm curious, is there any desire to move extract other core XBlock types as well? Specifically, I'm thinking things like:

• HTML Block
• Video Block
• Problem Block

We've run into places where we had wanted to add/extend behavior and were limited by the fact that these were too tightly integrated into platform to neatly override them. I've also done some thinking here so happy to help with scoping / discovery on that work.