Time discretized weak form double adding dt

To be fixed soon with incoming PR.

Essentially, we pass in `time_info.time()` when we evaluate the residual and jacobian associated with a weak form because functional takes `(double t, auto X, auto... inputs)`. Here t = t0 + dt. Then `time_discretized_weak_form` wraps around `functional_weak_form` by reconstructing a `time_info` from `t` and `dt`. This means `time_info.time()` called in the integrand (eg. time-dependent BCs) will give `t0 + dt + dt`.

Trace how time_info.time() is passed during residual and Jacobian evaluation, then follow the time_discretized_weak_form reconstruction around functional_weak_form. Verify that an integrand such as a time-dependent boundary condition observes t0 + dt rather than adding dt twice; the issue mentions an incoming PR but no file or test location.

Written by the indexing model from the issue text.