Warn about accessing props from `Object.prototype` in `.data()`/`jQuery.event.special`

[mgol]

Since 4.0, .data() no longer inherits from Object.prototype; the same applies to the events object from the private data store.

We should not restore the old behavior as that will reintroduce potential collisions with Object.prototype. We should, though, warn if a key matching a key from Object.prototype is read.

Let's also handle jQuery.event.special which underwent the same changes.

Ref jquery/jquery#4603
Ref jquery/jquery#5235

[mgol]

For 3.6.0, this is handled in #559; for 4.0.0, in #561.