[clang] [clang-format] Add an option to format integer and float literal case (PR #151590)

[Björn Schäpers via cfe-commits]

HazardyKnusperkeks wrote:

> I suggest `NumericLiteralCase`, `Prefix`, `HexDigit`, `ExponentLetter`, and `Suffix` for the option names and `Leave`, `Lower`, and `Upper` for the enum values. For example:
> 
> ```
> NumericLiteralCase:
>   Prefix:         Lower # 0x, 0b, etc.
>   HexDigit:       Upper # ABCDEF
>   ExponentLetter: Lower # e and p
>   Suffix:         Lower # ull, bf16, etc.
> ```

That is way better.

https://github.com/llvm/llvm-project/pull/151590