gh-35262: support calling PARI's qfbcornacchia() from BinaryQF
Recent versions of PARI have a `qfbcornacchia()` function which can
replace special cases of `qfbsolve()` while being much faster. In this
patch we add a path to `qfbcornacchia()` in the
`BinaryQF.solve_integer()` method; it can be selected using an optional
`algorithm=` argument. See the added doctest for an example of the
speedup.
Also fixes #35292.
URL: https://github.com/sagemath/sage/pull/35262
Reported by: Lorenz Panny
Reviewer(s): Lorenz Panny, Travis Scrimshaw
