Dataset5dstem torch native initial implementation (MAPED, time-series)

[bobleesj]

What problem this PR addreseses

DRAFT - will pull commits from #228 after merged.

~200 LOC changed - 90e7331

What should the reviewer(s) do

DRAFT

from_tensor:

dset5d = Dataset5dstem.from_tensor(
    torch.from_dlpack(data_cp),
    sampling=(0.5, 0.5, 0.46, 0.46),
    units=['A', 'A', 'mrad', 'mrad'],
    name='gold_3frame_stack',
    series_type='time',
    series=[0, 1, 2],

from_4dstem:

dset5d = Dataset5dstem.from_4dstem(
    [Dataset4dstem], series_type='time', series=[0, 1, 2, 3, 4, 5, 6],
)

This PR is limited to single GPU for now on purpose. Next PR can focus on multi GPU implementation.