(BIDS-2663) Add sorting to postgres query using pagination

[D13ce]

This PR adds sorting to the api1/validator/withdrawalCredentials/{withdrawalCredentialsOrEth1address} API endpoint to ensure correct pagination.

This should fix #2681.

[Eisei24]

utACK
I could not find withdrawal credentials where the API returned the wrong amount of validators on any network. Adding an ORDER BY would also not make a difference.

But if I interpret the bug as

• Make an API call with ?limit=200&offset=0 => Get 200 validator results
• Make an API call with ?limit=200&offset=200 => Get 200 validator results
• There are only ~390 different validators because they appear in both API calls

then the changes makes sense and should fix the issue.

[D13ce]

utACK I could not find withdrawal credentials where the API returned the wrong amount of validators on any network. Adding an ORDER BY would also not make a difference.

But if I interpret the bug as

* Make an API call with `?limit=200&offset=0` => Get 200 validator results

* Make an API call with `?limit=200&offset=200` => Get 200 validator results

* There are only ~390 different validators because they appear in both API calls

then the changes makes sense and should fix the issue.

I have written a small test program that iterates over 50k validators based on a single withdrawal credential. Without ordering, I have missed some every run. With ordering I received all 50k validators every run.