feat(wkt): convert to Prost's version of the WKT

[coryan]

We will need to convert to and from Prost's versions of the well-known
types. The same trait will be used to convert between our generated
types and the types that Prost generates.

Part of the work for #1384

[codecov]

Codecov Report

Attention: Patch coverage is 88.23529% with 6 lines in your changes missing coverage. Please review.

Project coverage is 95.74%. Comparing base (0644e87) to head (b1bc202).
Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
src/wkt/src/prost.rs	88.23%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1420      +/-   ##
==========================================
- Coverage   96.00%   95.74%   -0.26%     
==========================================
  Files          37       38       +1     
  Lines        1477     1528      +51     
==========================================
+ Hits         1418     1463      +45     
- Misses         59       65       +6     

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