Bug report: 32 and 64-bit fletcher checksums seem to be incorrect

**Describe the bug**
Fletcher-32 Checksum and Fletcher-64 Checksum algorithms seems not to be working as expected when using the "Generate all hashes" operation. Similar issue was reported last year in [1316](https://github.com/gchq/CyberChef/issues/1316).

**To Reproduce**
As an example, I have compared the results of the "Generate all hashes" operation with the online service [Convertcase.com](https://www.convertcase.com/hashing/fletcher-checksum). Fletcher-16 is identical, while Fletcher-32 is different. More can be seen in the screenshot. As mentioned, the Fletcher-64 checksum calculation does not seem to work either. I used the "Raw Bytes" encoding for the input characters (by default adjusted).

**Expected behaviour**
The Fletcher-32 for "security" should be 0x0f5a0378.
The Fletcher-64 for "security" should be 0x00000f5a00000378.

**Screenshots**
CyberChef vs. Convertcase.com

**Desktop:**
- OS: Kali Linux
- Browser: Google Chrome 18.0.5993.70 (Official Build) (64-bit)
- CyberChef version: 10.5.2

**Additional context**
It might also be that the [Convertcase.com](https://www.convertcase.com/hashing/fletcher-checksum) implementation is wrong.
Is the reported bug ([1316](https://github.com/gchq/CyberChef/issues/1316)) fixed and the latest CyberChef version (10.5.2) working properly in this regard?