EXPM: re-evaluate experimental

[jreback]

leave as experimental or change docs

• eval/query
• CustomBusinessDay
• msgpack DEPR: msgpack #27084 (deprecating)
• BigQuery
• Panel4D -> deprecated
• PanelND -> deprecated
• SQL changes
• r*flex methods
• get_options_data (ENH: Added method to pandas.data.Options to download all option data for... #5602)
• DataFrame.style

[jtratner]

r* flex methods too. They exist, but aren't in the docs yet and need to be tested a bit more. (We could also disable them entirely if you want).

[cpcloud]

should msgpack be added here?

[jreback]

yep