[SqlLab] 1-click tab closing in SqlLab

[gabe-lyons]

As discussed in the #superset slack group, I felt like the general consensus was adding 1-click to close SqlLab tabs would be nice. This was also a personal pet peeve of mine.

test plan:

• create a tab
• click the x button on a tab and verify it closes
• verify clicking the rest of the tab doesn't trigger a close
• run the specs

reviewers:
@michellethomas @williaster @graceguo-supercat
cc @mistercrunch @hughhhh @fabianmenges

[codecov-io]

Codecov Report

Merging #4738 into master will increase coverage by 0.02%.
The diff coverage is 94.73%.

@@            Coverage Diff             @@
##           master    #4738      +/-   ##
==========================================
+ Coverage   72.22%   72.24%   +0.02%     
==========================================
  Files         204      205       +1     
  Lines       15324    15343      +19     
  Branches     1181     1183       +2     
==========================================
+ Hits        11067    11085      +18     
- Misses       4254     4255       +1     
  Partials        3        3

Impacted Files	Coverage Δ
...javascripts/SqlLab/components/TabbedSqlEditors.jsx	91.74% <100%> (+0.07%)	⬆️
...ts/javascripts/SqlLab/components/TabStatusIcon.jsx	94.44% <94.44%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 11c9e67...f8a36b1. Read the comment docs.

[hughhhh]

This is dope! but i think we should make it really clear on how to close the tab. I think moving the down arrow to another location and putting the x there would be best. Not sure where we would put the dropdown though :p

[fabianmenges]

This is cool, does it make sense to just get rid of the drop down menu and move the "close" button to where the drop down is (the right side)?
The drop down contains only 2 elements that are not already on the main page, rename tab and hide tool bar. Rename tab could be triggered when you click on the name of the tab. Hide toolbar could just be a control on the page. Overall I'm still in favor of just getting rid of tabs in SQLLab all together and using the tabs of my browser.

[graceguo-supercat]

LGTM

[gabe-lyons]

@fabianmenges agree that would be an even better design- lets take care of that in a followup