This includes a few minor code changes:
- Removing redundant `lib.memory.Memory.Init = hdl.MemoryData.Init`
re-export;
- Renaming `FrozenError` to `FrozenMemory` and moving it to `.hdl`;
- Marking `ReadPort` and `WritePort` as `@final`.
The abbreviated form was initially added to match `lib.fifo`, but it
looks very out of place on `lib.memory`, and we may be moving away from
such heavy use of abbreviations anyway.
While technically a breaking change, these attributes have very narrow
usefulness and so this change qualifies as "minor".
Display `shape` and `depth` also. `depth` is redundant although useful
for ease of reading (there are always `depth` elements shown), but
`shape` was just lost.
This attribute is fully redundant with `.__len__()`, and is out of place
on a `list`-like container like `Memory.Init`.
The `.shape` attribute, however, provides a unique function.
