add(scan): Implement Results request

[oxarbitrage]

Motivation

We need to implement the Results request in order to later do the get_results grpc.

Close #8205

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Solution

Instead of just returning ids, this PR returns all data we have in a nested Tree. This data includes the corresponding key and height for each transaction hash found. A nested Tree structure is used to avoid repeating any data.

This version just returns all the results we have for the given keys. Height ranges or other tweaks were not included.

This request is less complex than others as no command needs to be sent to be scanner.

Testing

Test for the service is added, test for the sapling_results database function was not added as it is already tested by deletes_keys_and_results_correctly.

Review

Anyone can review. I am open to suggestions to improve it.

Reviewer Checklist

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Follow Up Work

#8163

[arya2]

This looks good, just needs a blocking thread for the disk reads.