v1.2.0: Add `clone()`, `nestInto()`; adjust lint rules

🌎 External changes

• Introduce new utility functions:
  • clone(): Duplicates a given object based on its prototype, optionally injecting new and/or modifying existing properties while preserving getters, setters, and other special members.
  • nestInto(): Nests a given series of keys into an object.
• Adjust lint rules:
  • Drop exemption of Jest mocks from import/export.
  • Drop exemption of TypeScript from react/jsx-props-no-spreading.
  • Turn off react/jsx-props-no-spreading.

🧹 Chores

• Upgrade dependencies.