[Feature]: Expand `read_image_any_rgb8` to support more image formats

Extend the extension-based dispatch in read_image_any_rgb8 so more common still-image formats are accepted, with clear errors and tests.

Motivation

Today only jpeg/jpg, png, and tiff are handled; anything else returns IoError::InvalidFileExtension. Users with WebP, BMP, GIF, etc. must call format-specific APIs manually, which hurts ergonomics and discoverability for “read any RGB8” workflows.

Proposed solution

• Add dispatch branches (or a small registry) for additional formats already supported elsewhere in the crate/workspace where applicable.
• Keep behavior explicit: decode to RGB8 (Rgb8) as the function name promises.
• Add unit/integration tests using small fixtures under tests/data (or reuse existing assets).
• Document supported extensions in the public rustdoc for read_image_any_rgb8.

Expected outcome

One-call loading works for a broader set of file types; errors remain typed (IoError) and documented.

✅ Acceptance criteria

• read_image_any_rgb8 handles at least the newly agreed format set (listed in doc comment).
• Tests cover each new extension (or magic-byte path if added).
• No breaking change to existing call sites without a semver-appropriate path (or document breaking change if API must change).
• cargo test -p kornia-io (with relevant features) passes.

Additional context

Separate from GStreamer video codecs (issue 9): this is file-based still image I/O. For a roadmap epic, link a parent issue “kornia-io format coverage.”

Code reference

pub fn read_image_any_rgb8(file_path: impl AsRef<Path>) -> Result<Rgb8<CpuAllocator>, IoError> {
    let file_path = file_path.as_ref().to_owned();

    // verify the file exists
    if !file_path.exists() {
        return Err(IoError::FileDoesNotExist(file_path.to_path_buf()));
    }

    // try to read the image from the file path
    // TODO: handle more image formats
    if let Some(extension) = file_path.extension() {
        match extension.to_string_lossy().to_lowercase().as_ref() {
            "jpeg" | "jpg" => read_image_jpeg_rgb8(file_path),
            "png" => read_image_png_rgb8(file_path),
            "tiff" => read_image_tiff_rgb8(file_path),
            _ => Err(IoError::InvalidFileExtension(file_path)),
        }
    } else {
        Err(IoError::InvalidFileExtension(file_path))
    }
}

Contribution Intent

• I plan to submit a PR to implement this feature.
• I'm requesting this feature but not planning to implement it.