[Cashtab] Patch extension build

Summary: The npm run extension script was failing due to the pnpm migration. Remove unused types from tsconfig.

Test Plan: pnpm run extension builds; pnpm run build also still builds, npm test

Reviewers: #bitcoin_abc, johnkuney

Reviewed By: #bitcoin_abc, johnkuney

Differential Revision: https://reviews.bitcoinabc.org/D19198