Add support for SVG

[Shashee99]

This PR adds support for detecting the SVG file format. Below are the details:

• File format: SVG (Scalable Vector Graphics)
• MIME type: image/svg+xml
• Detection confidence: detectConfident() — SVG files are identified with high certainty based on their distinct structure and signature.

Changes made:

1. Fixture file: Added fixture.svg to the fixtures directory.
2. Supported file types:
   • Added .svg extension to the extensions array in supported.js.
   • Added MIME type image/svg+xml to the types array in supported.js.
3. Detection logic: Added the logic for detecting SVG files in the core.js file.
4. Confidence category: Since the structure of SVG files is unique and easy to detect, this detection is classified under detectConfident().
5. Documentation:
   • Updated the "Supported file types" section of the README to include SVG in alphabetical order.
   • Added .svg extension to the keywords array in the package.json.

References:

• File format specification: SVG - W3C

[sindresorhus]

From the top of the readme:

This package is for detecting binary-based file formats, not text-based formats like .txt, .csv, .svg, etc.

There are also many things wrong with this pull request, and I also suspect it's AI generated based on the pull request description.

[Shashee99]

Thank you for your feedback! I understand now that this package is focused on detecting binary-based file formats. However, I added support for SVG because it is a common and well-defined format, and it includes a structured text format that is easy to detect programmatically (via its unique XML-based signature). While SVG is technically text-based, it’s used widely in many image processing workflows, which is why I thought it could be a useful addition.

[Borewit]

I wrote a file-type plugin for XML file types, which does detect SVG as well: @file-type/xml, which would be nice to mention somewhere in the README, as proposed in PR #708.