fix(): assigning canvas to collections

[ShaMan123]

Collections could be used as clip paths.
This PR fixes canvas assignment in such a case.
Because Group assigns canvas only if the property changed this should not affect performance.

[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  |   83.05 |    75.98 |   85.69 |   82.78 |                                               
 fabric.js |   83.05 |    75.98 |   85.69 |   82.78 | ...,30850,30924,30935-31000,31123,31222,31458 
-----------|---------|----------|---------|---------|-----------------------------------------------

[asturur]

The only thing we need to be careful of is determine what _set does and what set does.
Is fine to have one that is a bit higher level than another, important that is clear when to use one and another.

[ShaMan123]

I assumed set is a simple wrapper that accepts objects to iterate over and pass down to _set.