fix: Adding a new preprocess step to the include option

[Lucas-1048]

The preprocessing step works as follows: if a curly brace is found in the path, the function expand_brace_patterns() will be called on the patterns and will add the base path to the patterns within {}.

This resolves the issue where the first item inside {} was not considered. Furthermore, it ensures that only files and directories within the base path are included (before this change, the entire project references were being considered).

[ODAncona]

Hello @Lucas-1048,
Thank you for your contribution.
I wrote test and pushed them to main branch to check the correctness of your patch.

    fn test_brace_expansion_first_item() {
        let base_path = TEST_DIR.path();

        // This pattern uses brace expansion to match foo.py, bar.py, and baz.py
        // The issue was that the first item (foo.py) wasn't being considered
        let include_patterns = build_globset(&vec!["lowercase/{foo.py,bar.py,baz.py}".to_string()]);
        let exclude_patterns =
            build_globset(&vec!["lowercase/{qux.py,corge.py,grault.py}".to_string()]);
        let include_priority = false;

        // ALL files in the brace expansion should be included
        for file in ["foo.py", "bar.py", "baz.py"] {
            let path = base_path.join("lowercase").join(file);
            let relative_path = path.strip_prefix(base_path).unwrap();

            assert!(
                should_include_file(
                    &relative_path,
                    &include_patterns,
                    &exclude_patterns,
                    include_priority
                ),
                "Failed to include file: {}",
                file
            );
        }

        // Files not in the brace expansion should be excluded
        for file in ["qux.txt", "corge.txt", "grault.txt"] {
            let path = base_path.join("lowercase").join(file);
            let relative_path = path.strip_prefix(base_path).unwrap();

            assert!(
                !should_include_file(
                    &relative_path,
                    &include_patterns,
                    &exclude_patterns,
                    include_priority
                ),
                "Incorrectly included non-matching file: {}",
                file
            );
        }
    }
    ```
Congratulations 🥳 All tests pass. 

However, as I reviewed your PR, we handle the logic for an edge case that should be directed treated in the `globset` library. It doesn't make sense to fix it in `code2prompt` if the problem should be fixed upstream. Because fixing in `globset` directly would benefit all dependent projects and prevent the need for similar workarounds elsewhere ...

I will merge your code now anyway as a temporary fix. However, it shouldn't be a permanent solution. Could you directly investigate in the upstream `ripgrep` repo ?

Next steps:
 -  I redacted [an issue in the official repo](https://github.com/BurntSushi/ripgrep/issues/3018)
 - You should take a look at [Actual globset file](https://github.com/BurntSushi/ripgrep/blob/master/crates/globset/src/glob.rs)
 
 Thank you,
 
 Let me know what do you think about this ?
 
 Olivier