Update: finish implementing f_utf_character_is_valid() and related UTF-8 changes

Update: finish implementing f_utf_character_is_valid() and related UTF-8 changes

UTF-8 BOM is actually not a thing but only a suggestion, see RFC 3629.
I consider it a very bad practice now that I have learned that it is also the zero width space.
Get rid of the UTF-8 BOM support, it is a bad idea and is not to be supported by this project.

The referenced rfc also provides an easier way to view the valid ranges that my previous resources (such as wikipedia).
This helped me finish this function.

Updated byte_dump to better utilize this and to remove no longer necessary code.
Fix an accidental incorrect "invalid detection" check use before calling f_utf_character_is_valid() in byte_dump.
Explicitly print a "." or " " for UTF-8 control characters (ASCII control characters are already handled before this point so it is safe to call f_utf_character_is_control()).