fix: possible overflow in difficulty calculation (fixes #3923) companion

[jorgeantonio21]

Description
Quick fix to overflow problem in difficulty. This problem had already been settled for big_endian_difficulty.

Motivation and Context
In #4090, @CjS77 point it out that the little_endian_difficulty method had the same problem. This PR is an attempt to tackle it.

How Has This Been Tested?
Adapted tests from previous PR (#4090)

[CjS77]

Love the enthusiasm, but let #3923 get merged, and then rebase. :)
But looks good to me.

[jorgeantonio21]

Thanks for the encouragement @CjS77, I probably rushed a bit here. In the meanwhile, I will keep looking at the codebase :)

[CjS77]

#4090 is merged, so rebase / reset the changes to remove the conflicts and we should be good

[stringhandler]

Just need to resolve the conflicts here

[jorgeantonio21]

The PR should be ready to be merged ! Let me know if you have any additional comments/suggestions :)

[sdbondi]

@jorgeantonio21 Unfortunately, to merge this we need all commits to be signed.

You may also need to run this command to resign all commits:
git rebase --exec 'git commit --amend --no-edit -n -S' -i development

(might need to remove the command from the last merge commit d4cdac5 in the interactive rebase)

[jorgeantonio21]

@sdbondi I followed your instructions, if I haven't screwed up, commits should now be signed and the PR be ready to merge. Thanks for the advice !

[sdbondi]

@jorgeantonio21 Looks like it didn't take :/

[sdbondi]

@jorgeantonio21 I think if you make the commit over again it should work.

As in:

git reset --soft development
git commit -am "....."

[delta1]

@jorgeantonio21 I used this to get set up https://docs.github.com/en/authentication/managing-commit-signature-verification/signing-commits

Think there are some commits getting reverted here...