fix: prevent null initializing readonly members

[TimothyMakkison]

Prevent null initializing readonly members

Description

• Add check to container builder context for readonly members
• Added test

Fixes #653

Checklist

• The existing code style is followed
• The commit message follows our guidelines
• Performed a self-review of my code
• Unit tests are added/updated

[codecov]

Codecov Report

Merging #678 (46169e1) into main (71cbfdd) will increase coverage by 0.16%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #678      +/-   ##
==========================================
+ Coverage   90.81%   90.98%   +0.16%     
==========================================
  Files         172      172              
  Lines        6130     6132       +2     
  Branches      780      781       +1     
==========================================
+ Hits         5567     5579      +12     
+ Misses        387      377      -10     
  Partials      176      176              

Files Changed	Coverage Δ
...s/BuilderContext/MembersContainerBuilderContext.cs	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[github-actions]

🎉 This PR is included in version 3.2.0-next.1 🎉

The release is available on:

• GitHub release
• v3.2.0-next.1

Your semantic-release bot 📦🚀

[github-actions]

🎉 This PR is included in version 3.2.0 🎉

The release is available on:

• GitHub release
• v3.2.0

Your semantic-release bot 📦🚀