Change traits to booted

[lrljoe]

This PR changes the standard events to run on booted() rather than boot(), allowing mount() to take place first.

Additionally adds missing tests for:

• Using mount() in conjunction with builder()
• Ensure mount() is called prior to bundler() executing
• Ensuring that correct Exception is thrown if no columns are configured.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (c307360) 88.53% compared to head (ada2bce) 88.56%.

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #1603      +/-   ##
=============================================
+ Coverage      88.53%   88.56%   +0.03%     
  Complexity      1346     1346              
=============================================
  Files            106      106              
  Lines           3167     3167              
=============================================
+ Hits            2804     2805       +1     
+ Misses           363      362       -1     

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