Improve the path to displaying metrics on map

[sgreenbury]

Currently to display a metric on the map:

1. Search for metrics
2. Click preview tab
3. Click on the column name
4. Click to close the drawer (to see the map)

Some options include:

• In the search results table, currently "add" is the only available option. This adds the metrics to "selected metrics". As well as this, a button such as "show on map" could immediately display the metric from the search results on the map
• Upon clicking in 3. above, the draw could be closed so that 4. is no longer required
• A "Preview (map)" tab could be added where the drawer occupies a smaller part of the map and the metrics can be selected from the header of the previewed metrics