Epic: Resolve v6 -> v7 regressions

[lukekarrys]

In the RFC meeting on 2021-09-22 we discussed tracking/fixing regressions from npm6, and fixing those before npm8.

This is a (so far incomplete) list of those regressions I've found:

• [x] https://github.com/npm/cli/issues/3210
• [x] https://github.com/npm/cli/issues/2740
• [x] https://github.com/npm/cli/issues/3021

[ljharb]

We discussed trying to fix them in npm 7, specifically, to ease the upgrade path - ideally they wouldn't have to wait til npm 8.

There's also

• https://github.com/npm/cli/issues/2508
• https://github.com/npm/cli/issues/2610
• possibly https://github.com/npm/cli/issues/3256
• possibly https://github.com/npm/cli/issues/3671

[wraithgar]

• https://github.com/npm/cli/issues/3530
• https://github.com/npm/cli/issues/3175

[wraithgar]

• https://github.com/npm/cli/issues/3775

[wraithgar]

• https://github.com/npm/cli/issues/2606

[lukekarrys]

• https://github.com/npm/cli/issues/3863