Add v4 managed api entity

[eileenmcnaughton]

Note that this is searchable since it seems useful to me to be able to search these - albeit
for more advanced users!

@colemanw now passed

[civibot]

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[colemanw]

I would have voted to not make this searchable as this seems to be more of an internal entity. What's the use-case for searching it?

[eileenmcnaughton]

@colemanw it basically provides the equivalent of datatables for us to help out sysadmins to see what is going on - but I'm agnostic