Unit test for checking supported file formats

[oliver-pham]

We need to make sure this function:

silkie/silkie/utils.py

Lines 27 to 29 in 65024a5

	def is_filetype_supported(file_path: str) -> bool:
	file_extension = Path(file_path).suffix
	return definitions.SUPORTED_FILE_EXTENSIONS.count(file_extension) > 0

• return True if the file has one of the supported file extensions.
• return False if the file extension is not supported, invalid file path, or a path to a directory
• error handling for "bad" values (e.g. empty string, None) (this may need a fix)