giphy: Convert module to TypeScript.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

package.json

@@ -98,6 +98,7 @@
     "@babel/eslint-parser": "^7.11.3",
     "@babel/plugin-transform-modules-commonjs": "^7.19.6",
     "@formatjs/cli": "^6.0.0",
+    "@giphy/js-types": "^5.1.0",
     "@types/autosize": "^4.0.1",
     "@types/blueimp-md5": "^2.18.0",
     "@types/co-body": "^6.1.3",
@@ -116,6 +117,7 @@
     "@types/sortablejs": "^1.15.1",
     "@types/spectrum": "^1.8.4",
     "@types/textarea-caret": "^3.0.3",
+    "@types/throttle-debounce": "^5.0.2",
     "@types/tinycolor2": "^1.4.5",
     "@types/turndown": "^5.0.1",
     "@typescript-eslint/eslint-plugin": "^8.2.0",
@@ -141,6 +143,7 @@
     "mockdate": "^3.0.2",
     "nyc": "^17.0.0",
     "openapi-examples-validator": "^5.0.0",
+    "preact": "^10.24.3",
     "prettier": "^3.0.0",
     "puppeteer": "^23.5.0",
     "source-map": "npm:source-map-js@^1.2.1",