chore: remove all unused imports (#7999)

Removes all unused imports.

Temporarily swapped in
https://github.com/sweepline/eslint-plugin-unused-imports to
differentiate between unused imports and unused vars. The default rule
does not differentiate.

packages/richtext-slate/src/field/elements/h3/Heading3.tsx

@@ -3,7 +3,6 @@
 import React from 'react'
 
 import { useElement } from '../../providers/ElementProvider.js'
-import { Heading2Element } from '../h2/Heading2.js'
 
 export const Heading3Element = () => {
   const { attributes, children } = useElement()

packages/richtext-slate/src/field/elements/h4/Heading4.tsx

@@ -3,7 +3,6 @@
 import React from 'react'
 
 import { useElement } from '../../providers/ElementProvider.js'
-import { Heading2Element } from '../h2/Heading2.js'
 
 export const Heading4Element = () => {
   const { attributes, children } = useElement()

packages/richtext-slate/src/field/elements/h5/Heading5.tsx

@@ -3,7 +3,6 @@
 import React from 'react'
 
 import { useElement } from '../../providers/ElementProvider.js'
-import { Heading2Element } from '../h2/Heading2.js'
 
 export const Heading5Element = () => {
   const { attributes, children } = useElement()

packages/richtext-slate/src/field/elements/h6/Heading6.tsx

@@ -3,7 +3,6 @@
 import React from 'react'
 
 import { useElement } from '../../providers/ElementProvider.js'
-import { Heading2Element } from '../h2/Heading2.js'
 
 export const Heading6Element = () => {
   const { attributes, children } = useElement()