Use crc32c from abseil

[mering]

crc32c is available in abseil since 20230125: https://github.com/abseil/abseil-cpp/commit/1687dbf814eceb93de2d93f91b31acaab404091c.

Use this in order to reduce dependencies.

[coryan]

Unfortunately we promise to support Abseil >= 20200923, which does not include crc32c support:

https://github.com/googleapis/google-cloud-cpp/blob/main/doc/packaging.md#required-libraries

We should remove the dependency on crc32c on the 3.x release, where we will increase the minimum version for Abseil and (maybe) other deps.

[mering]

@coryan When do you plan to release 3.x?

[alevenberg]

The major release (3.x) is planned for 2024-12 or 2025-01

[mering]

@scotthart please include this in the next major release as well.