*Steps to reproduce:*

1. Create an action taking a ScriptableObject and add it to the graph.

2. Click the link button on the ScriptableObject link field for the action.

*Actual results:* 

Missing Assets tab to allow linking directly to an asset.

*Expected results:* 

Having an Assets tab to allow linking directly to an asset.

*Reproducible with versions:* 1.0.5

*Not reproducible with versions:* 

*Can’t test with versions:* 

*Tested on (OS):* Windows

*Notes:*
* Brought up in this discussion https://discussions.unity.com/t/support-for-custom-types-that-are-not-monobehaviours-or-scriptableobjects/1552467/3