Modern and default example images

[Blackbaud-AdamFunderburk]

Added default image examples for Input Box.
Removed two rows from the "States" list for default theme, since we have no hover or click states in default theme.

[blackbaud-ado]

Preview build at https://developer.blackbaud.com/skyux-forms?_sp.spa=pr-modern-and-default-example-images

[codecov]

Codecov Report

Merging #268 (ee44ad2) into master (19eabc0) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #268   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           37        37           
  Lines         1072      1072           
  Branches       200       200           
=========================================
  Hits          1072      1072           

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