Invalidate entries instead of a collection

[ryanmitchell]

👋 Thanks again for this add-on, its really useful.

This PR updates the approach to invalidate Entries themselves rather than the Collection, which still results in the collection rules being triggered:(https://github.com/statamic/cms/blob/801e954a054c0731e9890bb44be92970503cb6f9/src/StaticCaching/DefaultInvalidator.php#L62-L73)

The benefit of this is that you dont need to rely on rules for the invalidation - individual entry urls are invalidated regardless of whether they are in the rules.

If you're happy with this change, I'll raise a separate draft PR to support adding a query scope to the query (which relies on statamic/cms#5927 merging) which would allow dev's to add to the query (for example to add a ->orWhere('end_date', $now) on certain collections). I had the code all written but forgot that hadn't merged to core yet!

[martyf]

This is superb, thank you Ryan.

Another PR when the query scope gets merged is definitely appreciated!