silx view: Large 2D datasets are open

[t20100]

When opening a large 2D dataset containing many curves (shape: 1e6 x 3000, dtype: float32), it takes too long to display with the default view (raw?), while one want to browse the curves.

As a workaround, it is possible to open first another dataset and select the curves plot before selecting the 2D dataset.

It would be good to avoid this by either adding a confirmation before loading really large datasets or by changing the default view when the 2D data is really large.

Related to https://github.com/silx-kit/h5web/issues/1651