fix: handle merging of input and union types

[laststylebender14]

Summary:

• This PR adds support for both input and union type in type_merger.
• we merge the union and input types only when they're 100% same.

Issue Reference(s):
Fixes #... (Replace "..." with the issue number)

Build & Testing:

• [x] I ran cargo test successfully.
• [x] I have run ./lint.sh --mode=fix to fix all linting issues raised by ./lint.sh --mode=check.

Checklist:

• [x] I have added relevant unit & integration tests.
• [ ] I have updated the documentation accordingly.
• [ ] I have performed a self-review of my code.
• [ ] PR follows the naming convention of <type>(<optional scope>): <title>

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 99.83051% with 1 line in your changes missing coverage. Please review.

Project coverage is 86.23%. Comparing base (1e6d084) to head (1432cdf).

Files	Patch %	Lines
.../core/config/transformer/type_merger/similarity.rs	99.62%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2223 +/- ## ========================================== + Coverage 85.91% 86.23% +0.31% ========================================== Files 211 212 +1 Lines 19993 20440 +447 ========================================== + Hits 17177 17626 +449 + Misses 2816 2814 -2 ```

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