feat(dbus): Add grep function to search for patterns in a file

The new `grep` function reads a specified file and returns lines
containing a given pattern. It handles file not found errors and logs
unexpected exceptions, improving resilience in file operations.

src/revpi_middleware/dbus_middleware1/dbus_helper.py

@@ -41,3 +41,38 @@ def extend_interface(*args) -> str:
             the provided segments.
     """
     return ".".join([REVPI_DBUS_NAME, *args])
+
+
+def grep(pattern, filename):
+    """
+    Searches for lines in a file that contain a given pattern and returns them as a list.
+
+    The function reads lines from the specified file and checks whether each line
+    contains the provided pattern. It returns a list of lines that match the
+    pattern. If the file is not found, an empty list is returned. Any other
+    exceptions during the file reading process are caught and logged.
+
+    Args:
+        pattern (str): The substring to search for within the file's lines.
+        filename (str): The path to the file that will be searched.
+
+    Returns:
+        list[str]: A list containing lines that include the provided pattern, with
+        leading and trailing spaces removed.
+
+    Raises:
+        FileNotFoundError: This error is caught if the file specified is not
+        found.
+        Exception: Any unforeseen exception during file operations is caught and
+        logged.
+    """
+    try:
+        with open(filename, "r") as file:
+            # Gibt alle Zeilen zurück, die das Muster enthalten
+            matching_lines = [line.strip() for line in file if pattern in line]
+            return matching_lines
+    except FileNotFoundError:
+        return []
+    except Exception as e:
+        log.error(f"Error reading file: {e}")
+        return []