Fix isFinite for all kinds of sets

[konnov]

We now have different kinds of sets, including Int and Nat, and sets containing them. We should update isFinite to work correctly.

[shonfeder]

The current simulator definition of isFinite:

quint/quint/src/runtime/impl/compilerImpl.ts

Lines 702 to 705 in 8ff175a

	case 'isFinite':
	// at the moment, we support only finite sets, so just return true
	this.applyFun(app.id, 1, _set => just(rv.mkBool(true)))
	break

It's not clear to me what fixing means in this context.