fix: extension method parameters for existing target mappings

[trejjam]

Extension methods may generate invalid code

Description

Source

[Mapper]
class Mapper
{
  static partial void MapToB(this A value, B value);
}
class A {
    public int Value { get; set; }
}
class B {
    public int Value { get; set; }
}

Generates:

public partial class Mapper
{
    static partial void MapToB(this global::A source, this global::B target)
    {
        target.Value = source.Value;
    }
}

Notice this before the second parameter

Checklist

• The existing code style is followed
• The commit message follows our guidelines
• Performed a self-review of my code
• Hard-to-understand areas of my code are commented
• The documentation is updated (as applicable)
• Unit tests are added/updated
• Integration tests are added/updated (as applicable, especially if feature/bug depends on roslyn or framework version in use)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3e5ed87) 91.49% compared to head (c291aea) 91.49%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #923   +/-   ##
=======================================
  Coverage   91.49%   91.49%           
=======================================
  Files         215      215           
  Lines        7217     7217           
  Branches      872      873    +1     
=======================================
  Hits         6603     6603           
  Misses        408      408           
  Partials      206      206           

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[latonz]

Thank you for this PR!

[github-actions]

🎉 This PR is included in version 3.3.0-next.4 🎉

The release is available on:

• GitHub release
• v3.3.0-next.4

Your semantic-release bot 📦🚀

[github-actions]

🎉 This PR is included in version 3.3.0 🎉

The release is available on:

• GitHub release
• v3.3.0

Your semantic-release bot 📦🚀