Tabs in dashboard columns

problem / proposal For design reasons I’d like to nest tabs in columns.

context I implemented on a fork by moving onChangeTab to context. If this feature is desired I can fix tests, add nesting constraints, and PR. (Though idk if the nesting constraints are all that necessary)

[micimize]

@mistercrunch would still like to PR this unless it is controversial. The live version of the gif above is live on the aqdc now

[micimize]

@mistercrunch dashboards. Tabs on master can only be top-level or nested within other tabs, and I’m proposing allowing deeper/less constrained nesting for building layouts such as:

Here’s a compressed diff of my current changes to superset/assets/src/dashboard/util/isValidChild.js (would of course refine the depth limits in an actual PR):

const parentMaxDepthLookup = {
   // ...
   [DASHBOARD_GRID_TYPE]: {
-    [TABS_TYPE]: depthOne,
+    [TABS_TYPE]: depthFive,
   },
   // ...
   [TABS_TYPE]: {
-    [TAB_TYPE]: depthTwo,
+    [TAB_TYPE]: depthFive,
   },

   [TAB_TYPE]: {
-    [TABS_TYPE]: depthTwo,
+    [TABS_TYPE]: depthThree,
   },

   [COLUMN_TYPE]: {
     // ...
+    [TABS_TYPE]: depthFive,
   },
   // ...
}