Add towncrier

Author: dhirving

doc/changes/DM-52397.misc.md

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+`Butler.registry.queryDatasets`, `Butler.registry.queryDataIds`, and `Butler.registry.queryDimensionRecords` have been re-implemented using the same query framework backing `Butler.query()` and the various `Butler.query_*()` methods.  Though the `Butler.registry.*` methods are not yet deprecated, users are encouraged to begin migrating to the equivalent `Butler.query_*` functions.  The new implementation comes with a number of minor behavior changes:
+- We no longer raise an exception if governor dimension values in a query constraint are not known to the registry.  Instead, we return no results.
+- Result rows are now deduplicated.
+- `findFirst` searches are now supported in calibration collections.

doc/changes/DM-52397.removal.md

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 Removed deprecated `DatasetQueryResults.materialize()` method.
 Removed deprecated `offset` parameter from the `limit` method in the `DataCoordinateQueryResults`, `DatasetQueryResults`, and `DimensionRecordQueryResults` classes.
+Removed the deprecated feature where HTM and HEALPix spatial dimensions like `htm11` or `healpix10` could be used in data ID constraints passed to queries. The exception is `htm7`, which will continue to work.  Users should instead use region `OVERLAPS` constraints in query `where` expressions.
+Removed support for `<` and `>` operators in `Butler.registry.query*()` `where` strings for comparisons of `Timespan` vs `Timespan`, or `Timespan` vs `Time`.  Instead, use `timespan.begin < ts` or `timespan.end > ts` to explicitly indicate which timespan bound you are comparing with.