Install bioc and requested packages at setup stage

[native-api]

This allows the user to override install: without losing this critical part of R build logic.

See https://travis-ci.community/t/in-r-version-4-0-0-library-path-not-writable/9744/22?u=native-api for the user problem that this fixes. I also have trouble checking things out since I cannot get a large part of the logic without a dummy R package or override install: which is extremely inconvenient.

[native-api]

ping @jeroen @jimhester