Add msgpack mixin to dbtClassMixin

[gshank]

Supports dbt-core #10093.

Description

Enable using to_msgpack on objects with dbtClassMixin, and use of serialization context on __post_serialize__.

Checklist

• [x] I have read the contributing guide and understand what's expected of me
• [x] I have signed the CLA
• [x] I have run this code in development and it appears to resolve the stated issue
• [x] I have opened an issue to add/update docs, or docs changes are not required/relevant for this PR
• [x] I have run changie new to create a changelog entry

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 88.88889% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 56.29%. Comparing base (f0e2df6) to head (b7d45f8).

Files	Patch %	Lines
dbt_common/contracts/config/properties.py	80.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #125 +/- ## ========================================== + Coverage 56.26% 56.29% +0.03% ========================================== Files 50 50 Lines 3082 3082 ========================================== + Hits 1734 1735 +1 + Misses 1348 1347 -1 ``` | [Flag](https://app.codecov.io/gh/dbt-labs/dbt-common/pull/125/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dbt-labs) | Coverage Δ | | |---|---|---| | [unit](https://app.codecov.io/gh/dbt-labs/dbt-common/pull/125/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dbt-labs) | `56.29% <88.88%> (+0.03%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dbt-labs#carryforward-flags-in-the-pull-request-comment) to find out more.

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