feat: add JSON Schema Property helpers for allowed_values (enum) and examples

[aaronsteers]

Ref docs: https://meltano-sdk--1098.org.readthedocs.build/en/1098/typing.html#singer_sdk.typing.Property

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📚 Documentation preview 📚: https://meltano-sdk--1098.org.readthedocs.build/en/1098/

[codecov]

Codecov Report

Merging #1098 (e640769) into main (6cdb0fd) will increase coverage by 0.02%.
The diff coverage is 100.00%.

❗ Current head e640769 differs from pull request most recent head a48c7a2. Consider uploading reports for the commit a48c7a2 to get more accurate results

@@            Coverage Diff             @@
##             main    #1098      +/-   ##
==========================================
+ Coverage   83.41%   83.43%   +0.02%     
==========================================
  Files          40       40              
  Lines        3840     3846       +6     
  Branches      655      657       +2     
==========================================
+ Hits         3203     3209       +6     
  Misses        472      472              
  Partials      165      165              

Impacted Files	Coverage Δ
singer_sdk/typing.py	94.73% <100.00%> (+0.17%)	⬆️

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[aaronsteers]

@edgarrmondragon - Do you mind taking a quick look at this?

[edgarrmondragon]

lgtm!