feat(Layer): 3rd Patch of Group Rewrite ♦️

[ShaMan123]

Layer

This is pretty straight forward.
Subclass of Group.
Adapted layout logic to fit Layer's needs
Added logic in Group to support nesting Layer.
This is AMAZING because Layer can now be used to boost perf. We can split a canvas/group's objects into 2 sub collections, one for active objects and one for non active ones. We can then use Layer to render all the non actives and have it cached while setting group not to cache.

Gist

Layer will layout itself once it is added to a collection and by listening to it's parent layouts

• canvas - resize event (from the setDimensions method - should we listen to anything else? MutationObserver works both on web/node)
• group - layout event

Dev

Merge the 2nd patch, update from master and then merge this one.

View the diff

closes #3000
closes #7692

https://fx32zv.csb.app/

Cutting Edge

Read the comments below to see what can be achieved using Layer:

• feat(Layer): 3rd Patch of Group Rewrite ♦️ #7860 (comment)
• feat(Layer): 3rd Patch of Group Rewrite ♦️ #7860 (comment)
• feat(Layer): 3rd Patch of Group Rewrite ♦️ #7860 (comment)

[github-actions]

Code Coverage Summary

> fabric@5.1.0 coverage:report
> nyc report --reporter=lcov --reporter=text

-----------|---------|----------|---------|---------|-----------------------------------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s                             
-----------|---------|----------|---------|---------|-----------------------------------------------
All files  |   83.14 |    76.19 |   85.51 |   82.87 |                                               
 fabric.js |   83.14 |    76.19 |   85.51 |   82.87 | ...,31187,31261,31272-31337,31460,31559,31795 
-----------|---------|----------|---------|---------|-----------------------------------------------

[github-actions]

Code Coverage Summary

> fabric@5.1.0 coverage:report
> nyc report --reporter=lcov --reporter=text

-----------|---------|----------|---------|---------|-----------------------------------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s                             
-----------|---------|----------|---------|---------|-----------------------------------------------
All files  |   83.19 |    76.23 |   85.51 |   82.92 |                                               
 fabric.js |   83.19 |    76.23 |   85.51 |   82.92 | ...,31190,31264,31275-31340,31463,31562,31798 
-----------|---------|----------|---------|---------|-----------------------------------------------

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ShaMan123]

MAJOR update from master
7860.diff.txt from before