perf - use IdleValue for Collator creation to save ~25ms when starting without or with an empty explorer. fyi @bpasero

Revert "also use $mid as version id and only accept external and fsPath from the most recent version, #60163"

This reverts commit 7d80b00c.

This reverts commit 258f8dc8.

This reverts commit c537eaa1.

Using an overload makes the code more complex and prevents  patterns such as `.then(coalesce)` or `.map(coalesce)`. It also makes it clear which code paths are actually being most used in our code

also use $mid as version id and only accept external and fsPath from the most recent version, #60163

#60565

related to #60163