proposal: Add factory provide mode

[leaxoy]

First, this is a amazing project.

But now, both Provide and ProvideValue only support singleton likely mode, for Provide which only create value when first invoked. In sometimes, it's useful to create a new instance whenever it invoked.

[samber]

Hi @leaxoy,

It will be added to do@v2 🎉 -> #45

See "Transient services".