fix: transfer set

[Gozala]

This pull requests supersedes #3481 that passes transferables as sets instead of arrays (in order to avoid duplicates in them). However #3481 still kept using arrays during encoding and only afterwards it turned it into a set to eliminate duplicates.

This change instead updates type of transfer to set to eliminate intermediary arrays in favor of sets.

Fixes #3402

[Gozala]

Example seems to be failing because, webpack-cli get hoisted and instead of using local webpack@5 it uses hoisted webpack@4 and fails 😭

I'll try to figure out how to resolve this and push a fix, that said I think it's ready to be reviewed.

[Gozala]

I've spend couple of hours today trying to get the last test passing, but I could not work out the hoisting problem. I also tried to just update all webpack deps to webpack@5 but that broke aegir build which started to getting webpack@5 instead webpack@4 it expects.

[lidel]

@Gozala is this waiting for TS work to land first, or is it blocked on something else?

Does this PR close #3402? (if so, can you add the "Clsoes #.." to the description?)

[Gozala]

@Gozala is this waiting for TS work to land first, or is it blocked on something else?

This PR just needs to be updated to merge all the changes in the tree. However due to bunch of issues with duplicate deps in the tree (caused by TS Work) it's best to wait for that to settle instead of duplicating effort.