GET /works: omit id-less works

[lautarodragan]

https://github.com/poetapp/node/blob/b07b875e2cd6aa1474f5ae99e1b0a2feed4839a2/src/API/WorkController.ts#L59-L70

Update .find(filters, { projection: { _id: false } }) to something like

.find({ ...filters, id: { $exists: true } }, { projection: { _id: false } })