Request to make Query\Builder::runSelect method public

[daniser]

Sometimes I need to lock some rows in the table without fetching them.
The most efficient way to do this now is to call ->count() on query builder instance:

MyModel::where(...)->lockForUpdate()->count();

It's much faster than ->get(), but it'd much better if it'd be possible to call ->runSelect() directly, but as of now this method is protected.

Is there some elegant workaround for this or is ->count() maximum I can do?

[mfn]

I recently did "open" some other methods for similar reasons, see e.g. #34102

This PR was made before L8 was released. I'm mentioning this because I also made #33953 which eventually was reverted in L7 and then re-applied to L8, which was also still master back then. They reasons due to backward compatibility break, but I didn't realize understand why 🤔