The EllipticCurveHom_velusqrt class introduced in #34303 inherits from EllipticCurveHom (#32388, #32502), but it doesn't yet implement all of the required methods. In this patch, we add them.

Diff without the dependency: sagemath/sagetrac-mirror@7326051...8cb0f29

Depends on #34410

CC: @defeo @JohnCremona @tscrim @kwankyu

Component: elliptic curves

Author: Lorenz Panny

Branch/Commit: 8cb0f29

Reviewer: Travis Scrimshaw, Kwankyu Lee

Issue created by migration from https://trac.sagemath.org/ticket/34614