Fix yarn lint:types when matrix-js-sdk is not yarn linked. (#30612)

* Add missing dependencies on `@types` packages

Because we import the typescript source from matrix-js-sdk rather than the
`.d.ts` files, `tsc` ends up type-checking the js-sdk source. That means that
we need to have the `@types` packages that js-sdk needs.

* Add missing type definitions for `setInterval` and `setTimeout`

Our source assumes that `setTimeout` returns a number, not a
`Timeout`. If we `yarn link` js-sdk, then (somehow) we end up using the
definitions from there, but it's not really correct.

* Configure knip to ignore new deps

package.json

@@ -203,6 +203,7 @@
         "@testing-library/react": "^16.0.0",
         "@testing-library/user-event": "^14.5.2",
         "@types/commonmark": "^0.27.4",
+        "@types/content-type": "^1.1.9",
         "@types/counterpart": "^0.18.1",
         "@types/css-tree": "^2.3.8",
         "@types/diff-match-patch": "^1.0.32",
@@ -226,6 +227,7 @@
         "@types/react-dom": "19.1.7",
         "@types/react-transition-group": "^4.4.0",
         "@types/sanitize-html": "2.16.0",
+        "@types/sdp-transform": "^2.4.10",
         "@types/semver": "^7.5.8",
         "@types/tar-js": "^0.3.5",
         "@types/ua-parser-js": "^0.7.36",