File: Re-add support to skip CR (\r) in File::get_as_text

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.

.gitattributes

@@ -7,6 +7,8 @@ thirdparty/* linguist-vendored
 * text=auto eol=lf
 # Except for bat files, which are Windows only files
 *.bat eol=crlf
+# And some test files where the EOL matters
+*.test.txt -text
 
 # The above only works properly for Git 2.10+, so for older versions
 # we need to manually list the binary files we don't want modified.