New multi-campaign reports

[tstrg]

New multi-campaign reports with documentation described in the Readme file

[saschafoerster]

@tstrg It's not really related, sorry, but you seem like to have understood the reporting tool. Would you maybe be able to help repairing the reports back to work?
getCampaignClickStatistics
getCampaignLinkClickStatistics
I would like to send an RSVP email and find out who clicked on the "accept" link (to then get a ticket) and wo clicked on the "deny"-link.

When I am using them like this:

const results = await campaigns.getCampaignClickStatistics(inputs.campaign, ["*"]);
//or this 
const results = await campaigns.getCampaignLinkClickStatistics(inputs.campaign, ["*"]);

I get this error:

ReferenceError: asStream is not defined
    at _getCampaignLinkClickStatistics (/app/server/models/reports.js:468:9)
    at Object.getCampaignLinkClickStatistics (/app/server/models/reports.js:497:18)
    at evalmachine.<anonymous>:13:33
    at evalmachine.<anonymous>:36:3
    at Script.runInContext (vm.js:133:20)
    at Script.runInNewContext (vm.js:139:17)
    at main (/app/server/services/workers/reports/report-processor.js:93:16)

I tried to edit /app/server/models/reports.js and I changed:
async function _getCampaignLinkClickStatistics(campaign, select, unionQryFn, listQryFn)
to
async function _getCampaignLinkClickStatistics(campaign, select, unionQryFn, listQryFn, asStream)
but that didn't help. :) Maybe you know better?