Converts a string into canonical form, standardizing
such issues as whether a character with an accent
is represented as a base character and combining
accent or as a single precomposed character.
The normalization mode is NFKC (ALL COMPOSE). It standardizes
differences that do not affect the text content, such as the
above-mentioned accent representation. It standardizes the
"compatibility" characters in Unicode, such as SUPERSCRIPT THREE to
the standard forms (in this case DIGIT THREE). Formatting
information may be lost but for most text operations such
characters should be considered the same. It returns a result with
composed forms rather than a maximally decomposed form.