#2445 Add min, value, and max labels to range knob

[jeffcarey]

Issue: #2445

What I did

Added a simple display for the range slider for knobs of type Number: minimum on the left of the slider, and current value and maximum on the right of the slider.

How to test

Add a knob to a story: of type 'number' with range set to true. View the knobs panel for the story.
Expected: A slider appears with the minimum, current value, and maximum. The current value updates as you move the slider.

Is this testable with jest or storyshots?
No

Does this need a new example in the kitchen sink apps?
No (Appears in "official storybook" example).

Does this need an update to the documentation?
No

[codecov]

Codecov Report

Merging #3128 into master will decrease coverage by 0.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #3128      +/-   ##
==========================================
- Coverage   35.84%   35.83%   -0.02%     
==========================================
  Files         440      440              
  Lines        9632     9636       +4     
  Branches      911      902       -9     
==========================================
  Hits         3453     3453              
+ Misses       5602     5587      -15     
- Partials      577      596      +19

Impacted Files	Coverage Δ
addons/knobs/src/components/types/Number.js	7.46% <0%> (-0.48%)	⬇️
app/react/src/server/utils.js	0% <0%> (-100%)	⬇️
lib/core/src/client/manager/index.js	0% <0%> (ø)	⬆️
addons/knobs/src/react/WrapStory.js	49.42% <0%> (ø)	⬆️
...modules/ui/components/stories_panel/text_filter.js	30.98% <0%> (ø)	⬆️
...-native/src/preview/components/OnDeviceUI/index.js	0% <0%> (ø)	⬆️
addons/graphql/src/components/FullScreen/index.js	0% <0%> (ø)	⬆️
...tions/src/lib/types/function/createFunctionEval.js	77.77% <0%> (ø)	⬆️
lib/ui/src/modules/ui/components/menu_item.js	19.14% <0%> (ø)	⬆️
addons/knobs/src/angular/utils.js	82.14% <0%> (ø)	⬆️
... and 68 more

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[madhaze]

@jeffcarey nice. this looks great.