Tab Grid Fixes and Cleanup

[Gold872]

• Remove refresh() method
• Listen to state changes for each container model
• Use setter and getter methods for state notifying fields
• Remove tab grid field from list layouts

[codecov]

Codecov Report

Attention: Patch coverage is 67.05202% with 57 lines in your changes missing coverage. Please review.

Project coverage is 66.97%. Comparing base (8b9f784) to head (7d581ef).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/widgets/tab_grid.dart	58.75%	33 Missing ⚠️
...aggable_containers/draggable_widget_container.dart	40.00%	12 Missing ⚠️
...draggable_containers/models/list_layout_model.dart	56.25%	7 Missing ⚠️
...able_containers/models/widget_container_model.dart	91.22%	5 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #150   +/-   ##
=======================================
  Coverage   66.97%   66.97%           
=======================================
  Files          78       78           
  Lines        8114     8116    +2     
=======================================
+ Hits         5434     5436    +2     
  Misses       2680     2680           

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