Remove QuantizedArray class.

The is the final step in the transition to using `qwix.QArray`.

PiperOrigin-RevId: 834596328

Author: chr1sj0nes

qwix/_src/core/qarray.py

@@ -204,6 +204,9 @@ def take(x: jax.Array) -> jax.Array:
   return jax.tree.map(take, array)
 
 
+_VALID_SCALE_DTYPES = (jnp.float16, jnp.bfloat16, jnp.float32, jnp.float64)
+
+
 def validate_qarray(array: QArray):
   """Validates the internal consistency of a QArray."""
   if not isinstance(array.qvalue, jax.Array):
@@ -220,7 +223,7 @@ def validate_qarray(array: QArray):
     )
   if array.qvalue.dtype.itemsize > 1:
     raise ValueError(f'{array.qvalue.dtype} is not a valid type for qvalue.')
-  if array.scale.dtype not in (jnp.bfloat16, jnp.float32, jnp.float64):
+  if array.scale.dtype not in _VALID_SCALE_DTYPES:
     raise ValueError(f'{array.scale.dtype} is not a valid type for scale.')
   if array.zero_point is not None:
     if array.zero_point.ndim != array.qvalue.ndim: