Query log: Offer ability to determine number of rows shown.

### Problem Description
At present, Query log shows paginated data from querylog.json.

However, the limit of rows shown is hard coded. The user cannot choose how many rows to show.

This is inconsistent with other parts of the Management Interface, for example Settings > Client Settings.

### Proposed Solution
To both the top and bottom of Query Log, add a drop-down for the user to choose the number of rows shown on the screen.

### Alternatives Considered
No plausible alternatives identified.

### Additional Information
N/A