Filter active sponsors/backers and categorize correctly

[juergba]

Description

Our site mochajs.org is listing the avatars/links of our financial contributors at OpenCollective:

• all (active and cancelled) contributors are shown
• the distinction between sponsor and backer is incorrect. At the moment we only have one active sponsor.

Description of the Change

• The majority of monthly contributions (ORDER) has been cancelled by the contributors (ACCOUNT).
  We only select orders with ORDER.status===ACTIVE and ignore the cancelled ones.
• We use ORDER.tier set by OpenCollective for correct distinction (sponsors, backers).

Applicable issues

closes #4595