Implement needed SciJava Converters

Need to think about exactly which are needed, but here is a non-exhaustive list:
- [ ] `long[]` :arrow_right: `Dimension`
- [ ] `int` :arrow_right: `Shape`
- [x] `RandomAccessibleInterval` :arrow_right: `Iterable` (`Interval`)
- [ ] `Iterable` :arrow_right: `Histogram`
- [x] `RandomAccessibleInterval` :arrow_right: `IterableInterval`
- [ ] `ImagePlus` :left_right_arrow: `ImageDisplay`
- [ ] `ImagePlus` :left_right_arrow: `Dataset`
- [x] `Dataset` :left_right_arrow: `ImgPlus`
- [x] `Img` :left_right_arrow: `ImgPlus`
- [ ] `ImgView` and `LabelingView`
- [ ] Any other converters using [Views](https://github.com/imglib/imglib/blob/imglib2-2.0.0-beta-26/core/src/main/java/net/imglib2/view/Views.java)
- [ ] Use `TypeConverter` for images and type elements

Then we can remove tons of `Map` operations!

See the [convert_numbers branch](https://github.com/imagej/imagej-ops/compare/convert-numbers) for current progress.

Start by reviewing the `convert_numbers` branch and the linked `Views.java` implementation. Inventory which unchecked conversions are still needed, including the listed image, interval, histogram, view, and `TypeConverter` cases. Done means the required converters are implemented and the corresponding `Map` operations can be removed.

Written by the indexing model from the issue text.