Show instance sponsors if OC is set as donation url

What does this PR do?

This was requested by @piuvas on discord after the OC sponsor fetching was added.

All this does is expand the sponsors endpoint to add an instance boolean which is set to true on the instance information page.

It will check if a cached version exists first like the normal sponsor one does for the sharkey page.

If not then it checks the donationUrl is set and if it points to opencollective followed by it fetching all backers.

It then sorts by isActive and if Tier is set on user (otherwise it will show all backers) and then returns and caches it.

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requested review from @dakkar and @julia

added 3 commits

• dcd6eee6...b151d193 - 2 commits from branch develop
• 0897458c - Merge branch 'develop' into upd/instancesponsor

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added 4 commits

• 0897458c...72baaaab - 2 commits from branch develop
• e2010caa - Merge branch 'develop' into upd/instancesponsor
• 34cbf552 - upd: apply suggestion

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requested review from @dakkar

added 1 commit

• 6b459be1 - upd: move totalSponsors and donationUrl check

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resolved all threads

added 1 commit

• 9dd51bc9 - upd: fix donationUrl check position

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resolved all threads

added 1 commit

• f08ef28d - upd: fix broken returns and change if statement

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approved this merge request