Addon-a11y: fix design icons

[Armanio]

Issue:
I notice what in a11y tab in 'rules' list icons not visible. It's not good. Fix it!

What I did

Mini clean css in 'rules'
Fix 'rules' text position

How to test

1. Open official example
2. Click 'Accessibility' tab
3. Expand any rule
4. You don't see icons

For more information please look at screenshots:
Before:

After:

I work in macbook 17' without fullscreen monitor, open devtool panel broken a11y rules list. I fix icon width and rules text align. Look at screenshots:
Before:

After:

• Is this testable with Jest or Chromatic screenshots?
  no
• Does this need a new example in the kitchen sink apps?
  no
• Does this need an update to the documentation?
  no

[codecov]

Codecov Report

Merging #5991 into next will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             next    #5991   +/-   ##
=======================================
  Coverage   34.93%   34.93%           
=======================================
  Files         648      648           
  Lines        9515     9515           
  Branches     1351     1380   +29     
=======================================
  Hits         3324     3324           
  Misses       5574     5574           
  Partials      617      617

Impacted Files	Coverage Δ
addons/a11y/src/components/Report/Item.tsx	0% <ø> (ø)	⬆️
addons/a11y/src/components/Report/Rules.tsx	0% <ø> (ø)	⬆️

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