Force interface instead of type for better docs (#3815)

Typescript's type aliases (`type X = thing`) can refer to basically
anything, which makes it hard to write an automatic document formatter
for them. Interfaces on the other hand are only object, so they play
much nicer with docs. Currently, object-flavoured type aliases don't
really get expanded at all on our docs site, which means we have a bunch
of docs content that's not shown on the site.

This diff introduces a lint rule that forces `interface X {foo: bar}`s
instead of `type X = {foo: bar}` where possible, as it results in a much
better documentation experience:

Before:
<img width="437" alt="Screenshot 2024-05-22 at 15 24 13"
src="https://github.com/tldraw/tldraw/assets/1489520/32606fd1-6832-4a1e-aa5f-f0534d160c92">

After:
<img width="431" alt="Screenshot 2024-05-22 at 15 33 01"
src="https://github.com/tldraw/tldraw/assets/1489520/4e0d59ee-c38e-4056-b9fd-6a7f15d28f0f">


### Change Type

- [x] `sdk` — Changes the tldraw SDK
- [x] `docs` — Changes to the documentation, examples, or templates.
- [x] `improvement` — Improving existing features

scripts/lib/exec.ts

@@ -1,7 +1,7 @@
 import { execFile } from 'child_process'
 import { nicelog } from './nicelog'
 
-type ExecOpts = {
+interface ExecOpts {
 	pwd?: string
 	processStdoutLine?: (line: string) => void
 	processStderrLine?: (line: string) => void

scripts/lib/labels.ts

@@ -1,7 +1,7 @@
 import { join } from 'path'
 import { REPO_ROOT, writeJsonFile } from './file'
 
-type Label = {
+interface Label {
 	// this is what the label is 'called' on github
 	name: string
 	// this is how we describe the label in our pull request template

scripts/lib/publishing.ts

@@ -8,7 +8,7 @@ import { REPO_ROOT } from './file'
 import { nicelog } from './nicelog'
 import { getAllWorkspacePackages } from './workspace'
 
-export type PackageDetails = {
+export interface PackageDetails {
 	name: string
 	dir: string
 	localDeps: string[]

scripts/lib/workspace.ts

@@ -6,7 +6,7 @@ export type PackageJson = { name: string; private?: boolean; workspaces?: string
 	string,
 	any
 >
-export type Package = {
+export interface Package {
 	packageJson: PackageJson
 	relativePath: string
 	path: string

scripts/prune-preview-deploys.ts

@@ -6,7 +6,7 @@ import { nicelog } from './lib/nicelog'
 // `env` instead. This makes sure that all required env vars are present.
 const env = makeEnv(['CLOUDFLARE_ACCOUNT_ID', 'CLOUDFLARE_API_TOKEN', 'GH_TOKEN'])
 
-type ListWorkersResult = {
+interface ListWorkersResult {
 	success: boolean
 	result: { id: string }[]
 }

scripts/refresh-assets.ts

@@ -215,7 +215,10 @@ async function copyTranslations() {
 	// languages.ts
 
 	const languagesSource = await readJsonIfExists(join(sourceFolderPath, 'languages.json'))!
-	type Language = { label: string; locale: string }
+	interface Language {
+		label: string
+		locale: string
+	}
 	const languagesFile = `
 		/** @public */
 		export const LANGUAGES = ${JSON.stringify(