Adds Microwaveprop.Radio.TextSanitizer to remove BOM, zero-width
spaces/joiners, C0 control bytes (except CR/LF/TAB), and DEL, and to
collapse NBSP and other unicode whitespace into a regular space.
CSV: applied to the whole upload at the top of preview/2.
ADIF: applied per-field-value after extraction so the byte-counted
length tags still slice the right substring.
