This was removed in #63481, and we confirmed that it's better like this,
but we add back the possibility to strip CR as an option, to optionally
restore the previous behavior.
For performance this is done directly in `String::parse_utf8`.
Also fixes Android `FileAccess::get_line()` as this one _should_ strip CR.
Supersedes #63717.
Adds a few more complex edge cases which are supported.
Also adds some documentation, simplifies the code a bit and forbids using
double quotes as a delimiter.