codecs in the config

[d-v-b]

Our config object contains explicit parameterization of codecs, like {"name": "zstd", "configuration": {"level": 0, "checksum": False}}. I think it would be simpler to allow using just the name of the codec; the array creation routine would thus have some freedom to set codec parameters dynamically based on the user's input.

This is particularly relevant for the endian parameter of the bytes codec, which cannot be correctly specified without knowing the data type of the array. Right now our default is "little", but for single-byte dtypes this is technically wrong, and it requires modifying the default bytes codec definition on array creation time.