Sheaf cohomology on a site

Extensions of Mathlib's CategoryTheory/Sites/SheafCohomology/: the Čech complex of a covering family, its bicomplex with an injective resolution, and the comparison with derived sheaf cohomology. Every signature here uses an arbitrary site; the results for sheaves on a topological space, where a compact-open basis or flasqueness enters, live in Topology/Sheaves/Cech/.