ENH: Add IVIMFitSlicer extension

[Atakanisik]

This PR adds a new extension "IVIMfitSlicer" for Intravoxel Incoherent Motion (IVIM) diffusion analysis.

Key features:

• Voxel-wise parametric mapping and ROI-averaged statistical modeling.
• Supports Mono, Bi (Segmented/Free), and Tri-exponential models.
• Handles metadata parsing issues via manual presets.
• Pure Python extension using 'ivimfit' library.

Tier 1

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• Extension has a reasonable name (not too general, not too narrow, suggests what the extension is for). The extension name should not start with Slicer (unless it explicitly provides a bridge between Slicer and a tool or library), because it would make it more difficult to find extensions if the name of many started with the same word.
• Repository name is Slicer+ExtensionName (except if the repository that hosts the extension can be also used without Slicer)
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• Extension description summarizes in 1-2 sentences what the extension is usable (should be understandable for non-experts)
• Any known related patents must be mentioned in the extension description.
• LICENSE.txt is present in the repository root and the name of the license is mentioned in extension homepage. We suggest you use a permissive license that includes patent and contribution clauses. This will help protect developers and ensure the code remains freely available. MIT (https://choosealicense.com/licenses/mit/) or Apache (https://choosealicense.com/licenses/apache-2.0/) license is recommended. Read here to learn more about licenses. If source code license is more restrictive for users than MIT, BSD, Apache, or 3D Slicer license then describe the reason for the license choice and include the name of the used license in the extension description.
• Extension URL and revision (scmurl, scmrevision) is correct, consider using a branch name (main, release, ...) instead of a specific git hash to avoid re-submitting pull request whenever the extension is updated
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• Screenshot URLs (screenshoturls) are correct, contains at least one
• Content of submitted json file is consistent with the top-level CMakeLists.txt file in the repository (dependencies, etc. are the same)
• Homepage URL points to valid webpage containing the following:
  • Extension name
  • Short description: 1-2 sentences, which summarizes what the extension is usable for
  • At least one nice, informative image, that illustrates what the extension can do. It may be a screenshot.
  • Description of contained modules: at one sentence for each module
  • Publication: link to publication and/or to PubMed reference (if available)
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  • Click the settings icon next to About in the top-right corner of the repository main page and uncheck Releases and Packages (if they are currently not used)
• The extension is safe:
  • Does not include or download binaries from unreliable sources
  • Does not send any information anywhere without user consent (explicit opt-in is required)

Tier 3

Community-supported extensions.

• Documentation, tutorial, and test data are provided for most modules. A tutorial provides step-by-step description of at least the most typical use case, include a few screenshots. Any sample data sets that is used in tutorials must be registered with the Sample Data module to provide easy access to the user.
• Follows programming and user interface conventions of 3D Slicer (e.g., GUI and logic are separated, usage of popups is minimized, no unnecessary custom GUI styling, etc.)
• The extension can be successfully built and packaged on all supported platforms (Windows, macOS, Linux)
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• All requirements of tiers < 3.

Tier 5

Critically important extensions, supported by Slicer core developers. New Slicer Stable Release is released only if all Tier 5 extension packages are successfully created on all supported platforms.

• Slicer core developers accept the responsibility of fixing any issues caused by Slicer core changes; at least one Slicer core developer (anyone who has commit right to Slicer core) must be granted commit right to the extension's repository.
• Automated tests for all critical features.
• Maintainers respond to questions related to the extension on the Slicer Forum.
• All requirements of tiers < 5.

[Atakanisik]

@jamesobutler thanks for attention, when before i merge branch when its says out of date my json file complete all CI pipelines but after i merged to updateing the branch my json file failed with validation CI can you enlighten me about that?