Fix dumping of characters with non-standard sizes
- Prevent dumping of characters in DumpDataExtractor() with item_byte_size bigger than 8 bytes. This case is not supported by the code and results in a crash because the code calls DataExtractor::GetMaxU64Bitfield() -> GetMaxU64() that asserts for byte size > 8 bytes.
- Teach DataExtractor::GetMaxU64(), GetMaxU32(), GetMaxS64() and GetMaxU64_unchecked() how to handle byte sizes that are not a multiple of 2. This allows DumpDataExtractor() to dump characters and booleans with item_byte_size in the interval of [1, 8] bytes. Values that are not a multiple of 2 would previously result in a crash because they were not handled by GetMaxU64().