MWPW-160726: Implement Exit Prompt

[Blainegunn]

Resolves: MWPW-160726

Test URL: http://mwpw-160726--dc--adobecom.hlx.page/acrobat/online/test/sign-pdf?martech=off

[aem-code-sync]

This branch is ignored due to an invalid branch name. Branch names must:

• begin and end with alphanumeric characters
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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 18.18182% with 9 lines in your changes missing coverage. Please review.

Project coverage is 84.78%. Comparing base (e4e440a) to head (4b8c138).

Files with missing lines	Patch %	Lines
acrobat/blocks/verb-widget/verb-widget.js	18.18%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            stage     #869      +/-   ##
==========================================
+ Coverage   84.75%   84.78%   +0.03%     
==========================================
  Files          48       48              
  Lines        6114     6114              
==========================================
+ Hits         5182     5184       +2     
+ Misses        932      930       -2     

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