fix: change return value of ListContentAtACL and write test for it

[jhkimqd]

This PR introduces a few important changes to the ListContentAtACL function:

• Previously, the return value of ListContentAtACL was dynamic, and there were 756 unique combinations for the output (5, 2, 2). The nature of the db query could not be changed, but to make this much more predictable and testable, the previous return value has been split into 4 different strings - all combined to return a []string. The slice of strings contains the original output, in addition to three other outputs, separated by the table names:
  • combinedBuffers = append(combinedBuffers, buffer.String())
    combinedBuffers = append(combinedBuffers, bufferConfig.String())
    combinedBuffers = append(combinedBuffers, bufferBlockList.String())
    combinedBuffers = append(combinedBuffers, bufferAllowlist.String())
• The above change allows the function to be testable by not looking at all the possible combinations, but by looking at the individual table outputs, and checking whether the mocked values exist using strings.Contains