This change wraps the capacity_ member of CommonFields in a new HashtableCapacity class. This class encapsulates the logic for handling valid capacities and debug-only sentinel values like kMovedFrom and kDestroyed, improving type safety and clarity. Capacity-related helper functions are also reordered within the file to be defined before CommonFields.
The `capacity_` member is now part of the `HashtableInlineData` class, which was previously named `HashtableSize`. This change groups stack-allocated data members together.
This is necessary to make an experiment of storing capacity as 1 byte.
Having Capacity in the same struct would allow to use `data_` as bit-field.
PiperOrigin-RevId: 903283983
Change-Id: Ia5c05f6a476f5b32967737fcb626565948c1505d
d4d92a7009