Release v2.1.0rc1

Switch default encode_maps_as_lists_in_tables to "DATAAPIMAPS" (no observable changes w.r.t. previous releases)
Bugfix: fix payload encoding for empty maps/DataAPIMaps
User-defined types in tables:

• type management: CreateTypeDefinition, ListTypeDescriptor, AlterTypeOperation, AlterTypeAddFields and
  AlterTypeRenameFields classes
• type management: Database's create_type, list_type_names, list_types, alter_type and drop_type methods
• full support for UDTs in table ddl: Database.create_table()/Database.list_tables()/table.definition()
• UDT support in tables: introduced serializer_by_class and deserializer_by_udt serdes options
• UDT support in tables: introduced DataAPIDictUDT default dict-wrapper type

Tables, all index creation methods support a definition parameter, alternatively to the "column[+options]" call pattern
Tables, support for "text indexes":

• classes TableTextIndexDefinition and TableTextIndexOptions (e.g. for list_indexes() method)
• tables got a .create_text_index() method

Tables, introduced method list_indexes()
Cursors (all types): introduced the "pagination API":

• .fetch_next_page() method
• initial_page_state cursor constructor parameter / builder interface method

Admin, renamed 'region_name' ==> name in AstraDBAdminDatabaseRegionInfo and AstraDBAvailableRegionInfo (the old name kept as a deprecated alias)
Introduced the notion of 'passthrough columns' to cover all of the cql-only partially/completely unsupported columns in the read/schema-read path
Fix: methods drop_[collection|table] of [Async]Database, and their Collection/Table sugar methods, now consistently return None.
AstraDBAdmin: introduced [async_]find_available_regions() method (and related response objects)
embedding/reranking models' "API support status":

• db admins' .find_[embedding|reranking]_providers() methods have a filter_model_status parameter, with values in
  astrapy.constants.ModelStatus;
• returned *Model objects have an appropriate "API Support" attribute.

allow sending "$vector": None when inserting into collections
support for modelSupport in findRerankingProviders
CollectionDefinition fluent interface: set_lexical and set_rerank accept also just 'enabled'
find_and_rerank scores' type enlarged to: float|int|null

maintenance/internal stuff:

• improve integration test coverage for:
  • collection-columns in tables: indexing, collection-specific DML commands ($push, $pullAll and so on)
  • collections, lexical/BM25-related DDL operations (various analyzer configurations for)
  • collections, lexical/BM25-related DML operations (filtering, sorting based on $lexical)
  • tables, lexical/BM25-related DML
  • tables, logical filtering (i.e. $and, $or between clauses)
  • multiple vectorize columns in a Table
• subsumed the specific testing opt-in env. var 'ASTRAPY_TEST_MAP2TUPLES=y' into the catch-all 'cutting-edge main' ASTRAPY_TEST_LATEST_MAIN=y
• simplified SerdesOptions management in unit testing; some rationalization/refactoring of pre- and post-processing logic for tables in unit tests
• switched to uv (from poetry)
• promoted findAndRerank testing to the 'regular' IT (adjusted readme and env templates accordingly)
• pin h11 to 0.16.0 or higher (after a vulnerability report)
• switch to latest HCD for non-Astra CI github action
• introduce CQL-driven testing for low/no-support table columns. LOCAL_DATA_API_APPLICATION_TOKEN local test auth not supported anymore.