Returns the definitions of the codecs registered with registerCodec, in registration
order. The returned objects are snapshots: modifying them does not alter the registered codecs.
The CompressionStream and DecompressionStream classes of a codec registered with
CodecDefinition#codecURI only appear once the module has been imported, i.e. after the
first entry using the codec has been read or written.
Returns the definitions of the codecs registered with registerCodec, in registration order. The returned objects are snapshots: modifying them does not alter the registered codecs.