fix(styling): properly align flexbox ms-select icon+text vertically

[ghiscoding]

• the ms-select icon+text label was never fully aligned in the middle, this PR fixes that by taking more advantage of flexbox. See print screen below, note that it wasn't by much, just an offset of a pixel or 2 (icon was slightly lower than the text position) but with this PR change, they are perfectly aligned
• improve Material theme by increasing ms-select icon size
• also fix wrong Material theme color used in demo for ms-select

before

icon was slightly lower than text

after

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (a30d590) 99.8% compared to head (c2e67d5) 99.8%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #1397    +/-   ##
=======================================
  Coverage    99.8%   99.8%            
=======================================
  Files         199     199            
  Lines       21559   21559            
  Branches     7204    7068   -136     
=======================================
  Hits        21495   21495            
+ Misses         64      58     -6     
- Partials        0       6     +6     

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