Replace `TableNamePrefix` with `ITableNameFormatter` for Better Flexibility

[icanhasjonas]

Based on the suggestion from issue https://github.com/AllocZero/EfficientDynamoDb/issues/267

Currently, the API uses a TableNamePrefix string to modify table names. This works, but is inflexible.

This PR introduces an ITableNameFormatter interface to handle table name resolution. This allows for:

• Custom naming strategies (e.g., environment-based, hashing, localization)
• Cleaner separation of concerns
• Easier testing and mocking

Migration Path:

• Mark TableNamePrefix as [Obsolete]
• If TableNamePrefix is set, internally create a PrefixTableNameFormatter to maintain compatibility

This preserves backward compatibility while enabling greater extensibility.

Benchmark and Heap Alloc should have no- to minimal- effect. Size of passed argument (string? or ITableNameFormatter?) is the same. The formatter allows for non-heap formatting of table names (except for the simple formatter, which is more or less included for testing purposes)