Allow importing Mongoose without any MongoDB specifics, take 2

[vkarpov15]

Summary

#13902, but with cleaner git history.

We've been using this branch to make Mongoose playground work: https://github.com/mongoosejs/mongoose-playground/blob/b6032ccbbf11908ae45cfc8eb28077a5559bfbdf/package.json#L13 because otherwise there's no way to import fully fledged Mongoose in the browser.

This change is more a refactor than anything, but it is sufficiently significant that I wanted to hold off until Mongoose 8.

Examples

[hasezoey]

LGTM, a lot cleaner git history, though it seems like comparing HEAD to 8.0 still does not recognize the rename and making it more annoying to compare (but going commit by commit works)

just to confirm, the changes in lib/query.js are to make things consistent or was there a specific problem for this change? (the _collection.collection -> mongooseCollection change)

PS: should the old PR branch be deleted once this is merged?

[vkarpov15]

"just to confirm, the changes in lib/query.js are to make things consistent or was there a specific problem for this change? (the _collection.collection -> mongooseCollection change)" I don't remember the exact reasoning. The difference is that this._collection is an instance of mquery.Collection, whereas this.mongooseCollection is an instance of Mongoose's collection class. So I suspect there was some quirk with mquery collections that I didn't want to work around. Either way, I think using mongooseCollection is a maintainability improvement as we try to move away from mquery.