TiledDataset.plot() requires a slice_index even when it shouldn't

[Cadair]

Take this setup:

import dkist
from dkist.data.sample import VBI_AJQWW
ds = dkist.load_dataset(VBI_AJQWW)

first_tiles = ds.slice_tiles[0]
first_tiles

<dkist.dataset.tiled_dataset.TiledDataset object at 0x7fdfe527c2d0>
This VBI Dataset AJQWW is an array of (3, 3) Dataset objects and
consists of 9 frames.
Files are stored in /home/stuart/.local/share/dkist/VBI_AJQWW

Each Dataset has 2 pixel and 2 world dimensions.

The data are represented by a <class 'dask.array.core.Array'> object:
dask.array<getitem, shape=(4096, 4096), dtype=float32, chunksize=(4096, 4096), chunktype=numpy.ndarray>

Array Dim  Axis Name                  Data size  Bounds
        0  helioprojective latitude        4096  None
        1  helioprojective longitude       4096  None

World Dim  Axis Name                  Physical Type                   Units
        1  helioprojective latitude   custom:pos.helioprojective.lat  arcsec
        0  helioprojective longitude  custom:pos.helioprojective.lon  arcsec

Correlation between pixel and world axes:

                          |          PIXEL DIMENSIONS
                          | helioprojective | helioprojective
         WORLD DIMENSIONS |    longitude    |     latitude
------------------------- | --------------- | ---------------
helioprojective longitude |        x        |        x
 helioprojective latitude |        x        |        x

This dataset does not need any further slicing to be able to plot it.

In fact if you slice it it breaks horribly:

And passing what otherwise would be a valid slice breaks the logic for the title:

[Cadair]

We should probably call fig.tight_layout() or something at the end of .plot as well.