Runs the data loader registry (.fundsr$data_loaders) to populate (or refresh)
the package's storage environment (.fundsr_storage).
Details
The function temporarily sets the fundsr.reload option so that data loaders
can decide whether to recompute cached objects.
The previous value of getOption("fundsr.reload") is restored on exit,
even if a data loader errors.
Data loaders are taken from .fundsr$data_loaders and are called
sequentially in registration order. Each registered function must take
no arguments.