[9.x] Prevent calling count() on LazyCollection in Blade loops

[devfrey]

As described in #39003, looping over a LazyCollection using @foreach in Blade causes the entire collection's iterator to be unwound. This causes duplicate queries and unnecessary model hydration when using lazy collections with Eloquent (because everything would be loaded into memory – twice).

This change skips calling count() on lazy collections, which preserves its 'laziness' until actually looping over the items.

This PR could be considered a breaking change (therefore targeted towards 9.x), because certain information on the loop variable is lost. $loop->remaining, $loop->count, and $loop->last will be null after this change when looping over a lazy collection. If one would want to keep this behaviour, calling ->collect() on the lazy collection would mimic that.