Support Unicode Normalization Forms

[Colerar]

Unicode® Standard Annex #15 unicode-rs/unicode-normalization

NFC and NFD are particularly beneficial for macOS users. While APFS supports both NFC and NFD, many macOS APIs and applications automatically convert filenames to NFD. See: gist

NFKC and NFKD are useful for compatibility purposes. For example, it can convert Japanese squared characters like ㍿ and ㌀ to their compatible equivalents, such as 株式会社 and アパート. See: UAX #15: Examples of Compatibility Equivalence