deer: implement Deserialize for core::option

[indietyp]

🌟 What is the purpose of this PR?

Implements Deserialize for:

• core::option::Option

Taken from #1875

❗ Known Limitations

The current schema is problematic; it cannot accurately represent oneOf, and two different proposals to solve this are available as a prototype.

🔗 Related links

• deer implement Deserialize for built-in types (Part 2)  #1875
• GEN-160: deer type implementation #1700

🔍 Has this modified a publishable library?

This PR:

• modifies an npm-publishable library and I have added a changeset file(s)
• modifies a Cargo-publishable library and I have amended the version
• modifies a Cargo-publishable library, but it is not yet ready to publish
• modifies a block that will need publishing via GitHub action once merged
• does not modify any publishable blocks or libraries
• I am unsure / need advice

[codecov]

Codecov Report

Merging #2383 (1c29b14) into main (720c4dc) will increase coverage by 0.04%.
The diff coverage is 53.57%.

@@            Coverage Diff             @@
##             main    #2383      +/-   ##
==========================================
+ Coverage   60.69%   60.73%   +0.04%     
==========================================
  Files         313      314       +1     
  Lines       24199    24227      +28     
  Branches      421      421              
==========================================
+ Hits        14687    14714      +27     
- Misses       9507     9508       +1     
  Partials        5        5              

Flag	Coverage Δ
backend-integration-tests	3.66% <ø> (ø)
deer	69.59% <53.57%> (+0.20%)	⬆️
unit-tests	1.49% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
libs/deer/src/impls/core/option.rs	53.57% <53.57%> (ø)

... and 1 file with indirect coverage changes

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