fix: environment prop type updates

[silviuaavram]

What:

Fix the propTypes and TS for the environment prop in Downshift and hooks.
Refactor propTypes and use common objects.
Add scrollIntoView propType for hooks as it was missing.

Why:

Fix #834.

How:

Update the TS types to include the Node property in environment.
Update the propTypes:

    environment: PropTypes.shape({
      addEventListener: PropTypes.func.isRequired,
      removeEventListener: PropTypes.func.isRequired,
      document: PropTypes.shape({
        createElement: PropTypes.func.isRequired,
        getElementById: PropTypes.func.isRequired,
        activeElement: PropTypes.any.isRequired,
        body: PropTypes.any.isRequired,
      }).isRequired,
      Node: PropTypes.func.isRequired,
    }),

If the optional environment prop is used, it should contain all the properties listed above, as all of them are used.

Checklist:

• Documentation
• Tests
• TypeScript Types
• Flow Types
• Ready to be merged