Make root layout configurable

[midigofrank]

Description

• This PR makes the root layout configurable. This way we can use another root layout in thunderbolt.
• It also introduces a slot for additional header tags to be injected
• Pushes a workflow created event which is handled in js land

Validation steps

Check https://github.com/OpenFn/thunderbolt/pull/265 in order to test these changes.
At a minimum, everything should be working in Lightning as it was. The layout and workflow creation is not affected in any way

Pre-submission checklist

• I have performed a self-review of my code.
• I have implemented and tested all related authorization policies. (e.g., :owner, :admin, :editor, :viewer)
• I have updated the changelog.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.80%. Comparing base (f82dd42) to head (570f27c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2310      +/-   ##
==========================================
- Coverage   89.81%   89.80%   -0.01%     
==========================================
  Files         297      297              
  Lines       10133    10136       +3     
==========================================
+ Hits         9101     9103       +2     
- Misses       1032     1033       +1     

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