support setItems and getItems for operation batching

[ManUtopiK]

Describe the feature

I'm currently building a driver for gitlab. #199
I just forked the github driver, write tests, adapted fetchFiles and getItem for gitlab api, and done !

What I want to do is to provide a feature to setItem with a create/commit http post request.
But I don't want to commit each files one by one, I want to commit a bunch of files, with a commit message passed in opts and update the store internally with the http response.

A setItems function could be useful to do that. I think it could also be implemented for the github driver.

Additional information

• Would you be willing to help implement this feature?

[ManUtopiK]

Maybe also getItems, to fetch a bunch of files in one shot...

[pi0]

Both seems good ideas for support operation batching! PR more than welcome 💯

Core exposes them and reuses whenever driver allows. Otherwise falls back to individual setItem/getItem with Promise.all.

Only note to consider for getItems and little bit tricky to implement, is to call this on a path mountpoin when there is more than one driver mounted. We need to first map paths to their drivers and group the batches with sub-function calls.