HasPrimitives on disc

Stream: PR reviews

[Alex Kontorovich]

In #9598, @Ian Jauslin and I prove that holomorphic functions on discs have primitives. We have an approach that upgrades this to holomorphic functions having primitives on simply connected domains. (Then we'll have complex logs on the latter, square-roots, and, thanks to @Vincent Beffara's work, the Riemann Mapping Theorem...) Any comments/suggestions welcome!