Allow resetting myMdC by proposal number & (range of) run numbers

Description

We just needed to reset about 10 runs in an FXE proposal, but not the entire proposal. It's slow and error prone to get the run IDs from the web interface by hand. This MR allows using the existing script like this:

python3 -m webservice.update_mdc --flg A --proposal 3225 --runs 90-95

It will ignore runs that don't exist, so you could specify 1-9999 to reset an entire proposal.

I also added a simple dry-run by default to see what it would do - pass --really to actually make the changes.

How Has This Been Tested?

With a dry run as described above.

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• My code follows the code style of this project.

Reviewers

@roscar @hammerd @schmidtp