Missing blocks & block elements

[seratch]

Description

The following blocks and block elements are not yet supported.

blocks

• file blocks (for remote files)
• rich-text blocks

block elements

• multi-select elements
• checkboxes
• radio buttons
• input block's elements Adding Input Block Support for Modals #519
• rich text elements

• filtering options for conversations

What type of issue is this? (place an x in one of the [ ])

• bug
• enhancement (feature request)
• question
• documentation related
• testing related
• discussion

Requirements (place an x in each of the [ ])

• I've read and understood the Contributing guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've searched for any related issues and avoided creating a duplicate issue.