DM-25985: Add saving and checking of per-manager versions

[andy-slac]

For each manager we now store its full name, version number, and schema
digest. Some control for that has been moved to a separate interface
which needs to be implemented by each manager class. Saved manager name
could be different from one specified in registry config due to
difference in module names.

[TallJimbo]

Looks good, only minor comments.

One big-picture comment: why use multiple inheritance instead of just making all of the manager ABCs inherit from VersionedExtension? It looks like that's effectively required for all implementations anyway.

[TallJimbo]

typo: "The" -> "There"

[TallJimbo]

typo: "tim" -> "time"

[andy-slac]

Or Tim 😄

[TallJimbo]

Should we consider making these bytes instead of str, to move the burden of something like base64 or hex encoding out of implementations of this class, and into something common (and also guarantee that some encoding like that is used)? I assume that essentially all of the time they'll start out as bytes.

[andy-slac]

My concern here was that we need to save them in the database as strings because attribute table is a string -> string mapping. We could require bytes digests but then I'd need to convert them into string format (e.g. with hex encoding) when saving and convert back to bytes when reading. I decided to leave the choice for encoding to extension, besides there may be a case when digest can be produced as an actual human-readable string.

[andy-slac]

Re multiple inheritance - I was thinking that there may be some manager implementations that don't need version support (or may not even have database schema). Requiring those to implement versioning ABC looks like unnecessary burden. OTOH as you say all our current managers support versioning, so may be it will simplify things if we use versioning ABC as a base class for all of them, implementing that interface when version is not needed should be trivial task.