message: Improve GCP instance name construction
  The current code generates names by concatenating integers in a custom
  format, with unusual results.  For example, 2021-01-12 at 13:01:50 and
  2021-11-02 at 01:31:50 are both rendered as "2021112-13150".
  This change produces names like "2021-01-12t13-01-50", which is easier
  to read (and less likely to collide).
diff: @@ -26,8 +26,8 @@ import * as server_install from "./server_install";
  /** Returns a unique, RFC1035-style name as required by GCE. */
  function makeGcpInstanceName(): string {
  const now = new Date();
  - return `outline-${now.getFullYear()}${now.getMonth()}${now.getDate()}-${now.getUTCHours()}${
  - now.getUTCMinutes()}${now.getUTCSeconds()}`;
  + const isoMinusMilliseconds = now.toISOString().substring(0, 19);
  + return `outline-${isoMinusMilliseconds.toLowerCase().replace(/:/g, '-')}`;
  }
  // Regions where the first f1-micro instance is free.
  