Progress: f_utf unit tests and make significant change Unicode digit/decimal functions.

Progress: f_utf unit tests and make significant change Unicode digit/decimal functions.

The controller program is using f_utf_is_alphabetic_decimal().
The previous functionality of that function is now handled by f_utf_is_alphabetic_digit().

I reconsidered some of the design I implemented in the previous commit (e696e3941592c6910f2f8ecc87a698d4f618c3b4).
The design of reading the value for the variable "value" and then saving to it is too much complexity.
Simplify the design and just expect the caller to read the "value" and decide if it is or is not in range.

Get rid of the "*_is_decimal()" functions.
The "*_is_digit()" functions work like the "*_is_decimal()" functions did.
I am avoiding the term "decimal" because it refers to base-10.
The term "digit" is a bit more general.
The only downside is that fractions might fall under "digit" (really they are two digits), which this function currently does not handle.
The "*_is_numeric()" functions will recognize fractions.

I didn't get as far as I wanted to.
The number of Unicode values to assign has worn me down.
The tests processing is not complete and I haven't gone back and done my normal review.

I tried to keep the "value" as small as possible, but unsurprisingly some language out there has a digit that represents billions.
I am forced to use a 64-bit data type for this.