Fix input box focus state

[Blackbaud-AlexKingman]

#226

[blackbaud-ado]

Preview build at https://developer.blackbaud.com/skyux-forms?_sp.spa=pr-input-box-focus-check

[codecov]

Codecov Report

Merging #227 (d969ac8) into master (6b3bd07) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #227   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           29        29           
  Lines          869       884   +15     
  Branches       162       169    +7     
=========================================
+ Hits           869       884   +15     

Impacted Files	Coverage Δ
...file-attachment/file-attachment-label.component.ts	100.00% <100.00%> (ø)
...dules/file-attachment/file-attachment.component.ts	100.00% <100.00%> (ø)
...pp/public/modules/input-box/input-box.component.ts	100.00% <100.00%> (ø)

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