Provide an example to modify WCS of a DKIST `Dataset`

[yjzhu-solar]

Description

DKIST Dataset is based on NDCube, which does not provide a straightforward method to modify the WCS information. However, in data processing, it is often desired to coalign DKIST data, for example, VBI data, with HMI or AIA. It would be nice to provide an example on updating the WCS information restored in FITS and asdf files or the gwcs of the Dataset.

### Tasks
- [ ] Refactor the high-level parts of `dkist-inventory` so we can recommend users use it as a way to rebuild a gwcs.
- [ ] Potentially add a wrapper function in `dkist` which lets you "modify" your gwcs by doing input > change header table > new gwcs.
- [ ] Write an example using sunkit-image to do simple cross-correlation coalignment.