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

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

Additional details and impacted files

@@            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	Coverage Δ
unit	56.29% <88.88%> (+0.03%)	⬆️

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