DebugHexDecoder class

Converts various hex-formatted text into a Uint8List.

Parsing rules:

• Skip optional whitespace prefix.
• Skip optional location prefix (number + ":" + whitespace).
• Read the first group of hexadecimal digits — it must have an even number of digits.
• Every following non-whitespace group of equal or shorter length is parsed as bytes.
• Anything after the valid hex data on a line is ignored.

Examples of valid lines:

• 0000000: 0123 4567 89ab cdef 0123 4567 89ab cdef ................
• 0000010: 012345678 ............ # comment
• abcdef // no prefix