Simplify execution of various runs with different params

As an alternative to repeated (manual) executions of:

dvc exp run -S a=1
dvc exp run -S a=2

it might be usefull (and clean, I think) to allow some way to “pass several param files” (from a folder maybe), and this would “auto-queue” runs automatically accordingly.

[Houstonwp]

This is what Facebook’s Hydra does, and it really is intuitive and clean.

[behrica]

My main usecase for the feature request would be to auto-generate such parameter files. #8187 does not allow this. The parameters are interwoven with the rest of the exp run command.

This would allow to use any algorithm for calculating the concrete parameters, without the need to include all such algorithms in dvc itself.