title: Kusto select distinct on one column only
body: <p>Example Query -</p>
  <p>traces
  | project message, timestamp</p>
  <p>This outputs something like this -</p>
  <pre><code>message  |   timestamp
  ------------------------------
      A      2022-07-09 00:00:00
      B      2022-07-11 01:00:00
      A      2022-07-11 02:00:00
  </code></pre>
  <p>I want a query that gives this as output -</p>
  <pre><code>message  |   timestamp
  ------------------------------
      A      2022-07-09 00:00:00
      B      2022-07-11 01:00:00
  </code></pre>