Remove custom implementations of Map/MapWithDefault/OrderedSet

[maxscott]

#13815

MapWithDefault's usage in ember-data is accounted for here (emberjs/data/pull/5255)
OrderedSet should be installed as an addon by any project using it.

This keeps the vendor shim's 'ember-map'.default = Ember.Map, which is now native Map. Unsure if it's better to remove the alias/shim altogether.

[Turbo87]

Unsure if it's better to remove the alias/shim altogether.

IMHO it should be removed completely

@rwjblue why are there shims in this repo at all? I thought only ember-cli-shims provided them?! 🤔

[rwjblue]

@rwjblue why are there shims in this repo at all? I thought only ember-cli-shims provided them?! 🤔

They are not used here. We noop'ed them just before initial npm release (by simply not app.import'ing them) in #14808, but never came back to clean up. They should definitely be removed, but in a separate PR...

[rwjblue]

I submitted #15909 to remove.

[Turbo87]

@maxwerr can you rebase?

[maxscott]

@Turbo87 rebased. shims.js removed

[maxscott]

I figured today would be a good time to delete a bunch of private, seemingly unused code before someone else does! Lmk if this requires anything else I can do.

[Turbo87]

I've rebased this PR. CI is green. v3.5.0 has been released a long time ago. I'd say this is ready to be merged.

/cc @rwjblue

[rwjblue]

Thanks @maxscott and @Turbo87!