Review StreamResource and StreamDatum Schemas

[genematx]

Review the schemas of Stream Resource and Stream Datum documents to facilitate storage and client access.

Description

• Remove path_semantics from Stream Resource and Stream Datum schemas.
• Replace root and resource_path with uri. It may be a path on the local filesystem, file://localhost/{path}, a path on a shared filesystem file://{host}/{path}, to be remapped at read time via local mount config, or a non-file-based resource like s3://....
• Rename spec to mimetype and use MIME type values like application/x-hdf5. It is expected that any information about options like SWMR will be passed in the resource_kwargs (parameters, see below).
• Rename resource_kwargs to parameters. The word resource_ is a bit redundant here, and the word kwargs is a Python-ism.

Motivation and Context

This PR is based on the discussion and agreed recommendations made in Issue #296. The main motivation is to simplify and future-proof the access to data by consumers and clients, such as Tiled.

How Has This Been Tested?

Using existing tests (with renamed/replaced variables).

[DiamondJoseph]

As discussed in #296 I'm happy with the changes to go in, and as discussed with @coretl just now, I'm happy for this to go in so long as ophyd-async is pinned to <2.0 until after our experiment in June, then I'll adjust our deployed services. The implementation looks correct, just one repeated nit to make the history of changes a little clearer.

[danielballan]

I left some minor edits. Then I think this is good to go in.