This cleans up the install instructions to specify that optional libs
should be installed using the `kafka-python[opt]` format. This leverages
`setuptools`' `extra_requires` feature to let our users choose to
inherit any versions pins we might apply to our optional dependencies.

This also re-orders the docs slightly to give more visibility to the
`crc32c` install because users are unlikely to realize it exists.

It also cleans up the formatting of the compression libraries slightly,
as they were getting a little unwieldy.

Also re-order lexicographically.

Note that I did not exhaustively test this... there could be edge cases
depending on the python version. But I think we should be okay because
`tox.ini` is currently testing using with unpinned versions, so I think
we're already running these versions in our test suite.

Fix a deprecation warning in the newest version.

Previously there were two methods:
* `_find_coordinator_id()`
* `_find_many_coordinator_ids()`

But they do basically the same thing internally. And we need the plural
two places, but the singular only one place.

So merge them, and change the function signature to take a list of
`group_ids` and return a dict of `group_id: coordinator_id`s.

As a result of this, the `describe_groups()` command should scale better
because the `_find_coordinator_ids()` command issues all the requests
async, instead of sequentially blocking as the `described_groups()` used
to do.

Small cleanup leftover from https://github.com/dpkp/kafka-python/pull/2035

* Add consumergroup related errors
* Add DeleteGroups to protocol.admin
* Implement delete_groups feature on KafkaAdminClient