Selector: Re-expose jQuery.find.{tokenize,select,compile,setDocument}

Selector: Re-expose jQuery.find.{tokenize,select,compile,setDocument}

`Sizzle.tokenize` is an internal Sizzle API, but exposed. As a result,
it has historically been available in jQuery via `jQuery.find.tokenize`.
That got dropped during Sizzle removal; this change restores the API.

Some other APIs so far only exposed on the `3.x` line are also added
back:
* `jQuery.find.select`
* `jQuery.find.compile`
* `jQuery.find.setDocument`

In addition to that, Sizzle tests have been backported for the following
APIs:
* `jQuery.find.matchesSelector`
* `jQuery.find.matches`
* `jQuery.find.compile`
* `jQuery.find.select`

A new test was also added for `jQuery.find.tokenize` - even Sizzle was
missing one.

Fixes gh-5259
Closes gh-5263
Ref gh-5260
Ref jquery/sizzle#242
Ref gh-5113
Ref gh-4395
Ref gh-4406