mark highlighting not compatible with new process for ordering marks

[samussiah]

Hovering removes custom mark highlighting.

Test notes

• Add a custom mark via the text settings input:

  {
  "custom_marks": [
      {
          "per": [
              "USUBJID",
              "VISIT",
              "TEST",
              "STRESN"
          ],
          "type": "circle",
          "attributes": {
              "fill": "red",
              "fill-opacity": 1,
              "stroke": "black",
              "stroke-opacity": 1
          },
          "radius": 4,
          "values": {
              "DY": [
                  "56",
                  "112",
                  "168",
                  "224",
                  "280",
                  "336"
              ]
          }
      }
  ]
  }

• Verify that custom marks as well as default marks highlight as expected.
• Verify that custom marks as well as default marks can be clicked.
• Verify that custom marks maintain their visual characteristics, e.g. fill, stroke, etc.

[jwildfire]

Custom mark highlighting also makes it so that all non-highlighted points can't be clicked. Probably because code like this is returning the highlighted points instead of the raw points.

[danedexF5]

Tested all 3 bullet points, worked as expected