[reports] Refactor block component design for easier editor management

[greenrhyno]

Currently, Block.jsx creates a number of state-editing callbacks and various types of editors that use these callbacks, then passes these components as props to its child container component BlockEditor.jsx. This clutters Block.jsx and makes it instantiate many things that are not needed for the current state of the Block Editor. It also confuses the control flow of data.

Task: Make Block.jsx only responsible for the maintaining of local blockState (a working copy of what is saved in the database) then make BlockEditor handle the creation of BlockType-specific editors and their methods needed for updating blockState. Then, have its children editors (whether code editors or "simple" UI editors) implement the BlockType-specific logic for updating the blockState. Also add a consistent, general way for specific block editors to validate their changes.

To do:

• Move all blockState-editing methods to BlockEditor
• Make the getting of block variables (useVariables) consistent
• Make RichTextEditor a type of SimpleUI-type component rather than a separate thing
• Have BlockElement handle isValidWorkingState state
• Pass setIsValidWorkingState() down to BlockEditor
• Wrap state-editing methods created in BlockEditor so that they automatically update isModified and isValidWorkingState variables