Adjust DBS Client to aggregate data from dbs1go server

[vkuznet]

Upon discussion within DMWM we agreed to adjust DBS Client to aggregate data from dbs2go server. This issue is a placeholder with requirements, which are the following:

• add aggregation functionality to sub-set of DBS APIs, e.g. runs, etc., see full discussion in Difference in DBS python vs dbs2go result output WMCore#10841
• add additional option to perform aggregation, and make it true by default. This will allow later to change the default to false (i.e. do not perform aggregation) and make it transparent to upstream users of DBS client
• ensure that DBS Client will work transparently with existing Python server and new dbs2go one
• once all changes will be place make new release and install it with CMS software stack (WMA, CRAB, etc.) such that DBS Client will be ready for migration from Python to Go based DBS srever

[vkuznet]

@klannon , @amaltaro , @yuyiguo this is a placeholder ticket to list set of requirements we discussed will be required to complete migration to Go based DBS server. Please review and add/change necessary items.

[vkuznet]

for the record, I'll do all the changes and provide appropriate PR to satisfy listed set of requirements.

[vkuznet]

@amaltaro , @yuyiguo please let me know which branch I should use to start the development.

[klannon]

I may be wrong, but I think we'd want to use the new client only repository for this, wouldn't we?

[vkuznet]

ok, closing this one in favor of dmwm/DBSClient#19