Add legacy MD5 Minter

Submitting this for discussion.

Interested in ideas about more robust testing of edge cases for existing ID's. This needs to be able to replicate https://github.com/dpla/ingestion/blob/develop/lib/akamod/select-id.py#L55
To clarify, this only impacts Primo _collections_, which don't have their own identifiers exposed in the data we're pulling from MWDL or Getty. IDs for Primo collections are generated in our old ingestion code in a slightly convoluted way:

* Grab the source name: e.g. `mwdl`
* Pull data from the element used as the source for `edm:dataProvider` (e.g. `<lds03/>` for MWDL, sample data: `University of Utah`)
* Pull data from the element for the source used as the collection title (e.g. `<lsr13/>` for MWDL, sample data: `University of Utah UScholar Works`)
* Join those three values with `--`: `mwdl--University of Utah--University of Utah UScholar Works`
* Normalize each space to a single `_`: `mwdl--University_of_Utah--University_of_Utah_UScholar_Works`
* Encode to UTF-8 and then generate the MD5: `cca6e98a271f1b6e541142e3ddeabd0f`