Extensible codecs for V3 (zarr-developers#1588)

* Pull Zarrita into Zarr-Python @ 78274781ad64aef95772eb4b083f7ea9b7d03d06

No code changes to Zarrita were made.

* apply zarr lint rules

* zarrita -> v3

* v3/abc [wip]

* use abcs plus implementation notes

* working on making codecs extensible

* adds index_location

* adds support for codec entry points

* adds tests from zarrita

* fixes types

* Apply suggestions from code review

Co-authored-by: Joe Hamman <jhamman1@gmail.com>

* remove test codec from pyproject.toml

---------

Co-authored-by: Joseph Hamman <joe@earthmover.io>
Co-authored-by: Joe Hamman <jhamman1@gmail.com>

.pre-commit-config.yaml

@@ -32,3 +32,4 @@ repos:
         additional_dependencies:
           - types-redis
           - types-setuptools
+          - attrs