Add placeholder product for fill scheme and use in Ecal Local Reco

Add placeholder FillSchemeInfo product which contains only the bunch spacing for now, but should contain the full filling scheme in the future.

Dummy producer added which fills bunch spacing from PileupSummaryInfo for MC and from hardcoded run list for data.   (n. b. the bunchSpacing parameter in the default mixing nopileup config was changed to be easily distinguishable from 50ns and 25ns, but this should have no physics effect)

Ecal local reco modified to use the FillSchemeInfo (but only switching between 10pulse config for 25ns and 5pulse config for 50ns for now)

@bachtis @emanueledimarco @argiro @lgray

Hi Slava,
I was trying to keep the number of special cases to a minimum.  The Ecal use case currently only switches between 25 and 50 anyways.  A proper solution obviously needs the proper solution from lumidb/dip/whatever.