[core-api][experimental] multi partition mappings

[OwenKephart]

Summary & Motivation

decision: experimental -> public
reason: these APIs have existed for many years without change, and are intertwined with serialized objects, making it extremely unlikely that we would change them
docs exist: yes (api only, which is ok)

How I Tested These Changes

Changelog

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[OwenKephart]

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• [core-api][deprecated] Confirm all simple deprecations #26712
• [core-api][experimental] include_sources -> include_external_assets #26710
• [core-api][experimental] repository_def in RunStatusSensorDefinition #26709
• [core-api][experimental] allow_nonexistent_upstream_partitions #26708
• [core-api][experimental] observable_source_asset, multi_observable_source_asset #26706
• [core-api][experimental] Definitions.get_all_asset_specs, Definitions.with_reconstruction_metadata #26705
• [core-api][experimental] execution type #26695
• [core-api][experimental] freshness_policy param #26702
• [core-api][experimental] custom_path_fs_io_manager #26679
• [core-api][experimental] Definitions.merge #26704
• [core-api][experimental] create_repository_using_definitions_args #26703
• [core-api][experimental] DataVersion assorted APIs #26698
• [core-api][experimental] AssetSelection.tag #26697
• [core-api][experimental] Table metadata #26692
• [core-api][experimental] BackfillPolicy #26694
• [core-api][experimental][PLACEHOLDER] create beta decorator #26691
• [core-api][experimental] direct resource passing #26688
• [core-api][experimental] multi partition mappings #26686 👈 (View in Graphite)
• [core-api][experimental] AMP #26685
• [core-api][experimental] get_asset_provenance #26684
• [core-api] base #26770 : 1 other dependent PR (#26707 )
• master

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[yuhan]

i know this API itself is unlikely to change, but im wondering if we should mark it as "Beta" for the following reasons:

• its functionality is still limited given "Multipartitions definitions are currently limited to two dimensions" (docs)
• i know jarred/sean are scoping some partition improvements, so maybe there's a chance for some holistic partition improvements including this API's functionality, so i kinda want to keep the possibility of making changes to it.