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

[Owen Pan via cfe-commits]

owenca wrote:

I suggest `Prefix`, `HexDigit`, `ExponentLetter`, and `Suffix` for the sub-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.
```

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