feat: add filepath package with dir() function

The filepath package helps work with file paths in KCL. This commit adds:
- dir() function to get directory name from path
- Comprehensive test cases
- Package documentation and metadata

Signed-off-by: suin <[email protected]>

Author: suin

filepath/README.md

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+# filepath
+
+A KCL package that helps you work with file paths. It provides functions to handle file paths in a safe and consistent way.
+
+## Installation
+
+To install this package, run the following command:
+
+```bash
+kcl mod add oci://ghcr.io/appthrust/kcl/filepath
+```
+
+## Usage
+
+### dir()
+
+The `dir()` function returns the directory name of a path, similar to Python's `os.path.dirname()`.
+
+```python kcl
+import filepath
+
+# Basic usage
+dir = filepath.dir("/home/user/file.txt")  # Returns "/home/user"
+```

filepath/dir.k

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+dir = lambda path: str -> str {
+    """Returns the directory name of a path."""
+    ret = "."
+    if path == "":
+        ret = "."
+    elif path == "/":
+        ret = "/"
+    elif path[0] == "/" and path.strip("/") == "":
+        ret = "/"
+    else:
+        parts = path.rstrip("/").rsplit("/", 1)
+        len = len(parts)
+        if len > 1:
+            if parts[0] == "":
+                ret = "/"
+            else:
+                ret = parts[0].rstrip("/")
+
+    ret
+}

filepath/dir_test.k

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+test_basic_unix_path = lambda {
+    assert dir("/home/user/file.txt") == "/home/user"
+}
+
+test_trailing_slash = lambda {
+    assert dir("/home/user/") == "/home"
+}
+
+test_root_level_file = lambda {
+    assert dir("/file.txt") == "/"
+}
+
+test_filename_only = lambda {
+    assert dir("file.txt") == "."
+}
+
+test_current_directory = lambda {
+    assert dir(".") == "."
+}
+
+test_current_directory_with_slash = lambda {
+    assert dir("./") == "."
+}
+
+test_parent_directory = lambda {
+    assert dir("..") == "."
+}
+
+test_parent_directory_with_slash = lambda {
+    assert dir("../") == "."
+}
+
+test_root_directory = lambda {
+    assert dir("/") == "/"
+}
+
+test_empty_string = lambda {
+    assert dir("") == "."
+}
+
+test_multiple_slashes = lambda {
+    assert dir("/home//user///file.txt") == "/home//user"
+}
+
+test_multiple_current_directories = lambda {
+    assert dir("./././file") == "././."
+}
+
+test_multiple_parent_directories = lambda {
+    assert dir("../../../file") == "../../.."
+}
+
+test_triple_dots = lambda {
+    assert dir(".../file") == "..."
+}
+
+test_path_with_current_directory = lambda {
+    assert dir("/home/user/./file") == "/home/user/."
+}
+
+test_path_with_parent_directory = lambda {
+    assert dir("/home/user/../file") == "/home/user/.."
+}
+
+test_path_with_spaces = lambda {
+    assert dir("/path/with spaces/file") == "/path/with spaces"
+}
+
+test_path_with_tab = lambda {
+    assert dir("/path/with\tTab/file") == "/path/with\tTab"
+}
+
+test_path_with_unicode = lambda {
+    assert dir("/ユーザー/ファイル") == "/ユーザー"
+}
+
+test_path_with_hash = lambda {
+    assert dir("/path/with#hash/file") == "/path/with#hash"
+}
+
+test_path_with_query = lambda {
+    assert dir("/path/with?query/file") == "/path/with?query"
+}
+
+test_multiple_root_slashes = lambda {
+    assert dir("////////") == "/"
+}

filepath/kcl.mod

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+[package]
+name = "filepath"
+edition = "v0.10.0"
+version = "0.0.2"