ENH: Expose ArrowIntervalType and ArrowPeriodType in the public API

[mroeschke]

In cuDF (rapidsai/cudf#11617 (comment)), ArrowIntervalType is used when creating a cuDF column from an interval arrow array (that can original from pandas). Would it make sense to expose ArrowIntervalType and ArrowPeriodType in the public API?

cc @jorisvandenbossche @shwina @galipremsagar

[jbrockmendel]

any particular reason not to parametrize these like the others?

[mroeschke]

IIUC these are conceptually different than pd.ArrowType as they are pyarrow extension types (subclass pyarrow.ExtensionType) necessary convert pandas Interval & Period types to pyarrow via __arrow_array__ (? cc @jorisvandenbossche)