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[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

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

Additional details and impacted files

```diff @@ 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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