DM-39605: Use butler.dimensions rather than butler.registry.dimensions

doc/changes/DM-39605.misc.rst

@@ -0,0 +1,4 @@
+* Replace usage of ``Butler.registry.dimensions`` with ``Butler.dimensions``.
+* Modernize type annotations.
+* Fix some documentation problems.
+* Minor modernizations to use set notation and f-strings.

doc/lsst.daf.butler/organizing.rst

@@ -14,7 +14,6 @@ We call a `DatasetRef` whose `~DatasetRef.id` attribute is not `None` a *resolve
 
     In most data repositories, dataset IDs are 128-bit UUIDs that are guaranteed to be unique across all data repositories, not just within one; if two datasets share the same UUID in different data repositories, they must be identical (this is possible because of the extraordinarily low probability of a collision between two random 128-bit numbers, and our reservation of deterministic UUIDs for very special datasets).
     As a result, we also frequently refer to the dataset ID as the UUID, especially in contexts where UUIDs are actually needed or can be safely assumed.
-    But 64-bit autoincrement integers are also supported (albeit mostly for legacy reasons), and we continue to use "dataset ID" in most code and documentation to refer to either form.
 
 Most of the time, however, users identify a dataset using a combination of three other attributes:
 

python/lsst/daf/butler/__init__.py

@@ -16,5 +16,5 @@
 
 # Import the registry subpackage directly for other symbols.
 from .registry import CollectionSearch, CollectionType, Registry, RegistryConfig
-from .transfers import YamlRepoExportBackend, YamlRepoImportBackend
+from .transfers import RepoExportContext, YamlRepoExportBackend, YamlRepoImportBackend
 from .version import *