As mentioned in
https://github.com/fish-shell/fish-shell/pull/9688#discussion_r1155089596,
commit b77d1d0e2b (Stop crashing on invalid Unicode input, 2024-02-27), Rust's
char type doesn't support arbitrary 32-bit values. Out-of-range Unicode
codepoints would cause crashes. That commit addressed this by converting
the encoded bytes (e.g. UTF-8) to special private-use-area characters that
fish knows about. It didn't bother to update the code path in builtin read
that relies on mbrtowc as well.
Fix that. Move and rename parse_codepoint() and rename/reorder its input/output
parameters.
Fixes#11383
(cherry picked from commit d9ba27f58f)
bc3e3ae029