feat(types)!: camelCase enum serialization; Bump polkadot/api@v4 w/ ESM

BREAKING CHANGE
Enums in responses serialize with [camelCase variants](https://github.com/polkadot-js/api/pull/3024). Check spec diffs for details

Other changes
- Reverses regressions in decoding blocks with [sudo proxy variants](https://github.com/polkadot-js/api/pull/3286)
- Updates jest.config to treat `.js` files as ESM - transforming @polkadot/* packages from ESM to CJS.
- Bump deps