Update rush and pnpm to support node 12 and 14

[timotheeguerin]

Node 10 is ending its life in april 2021. Current active LTS version is Node 14.

This PR updates rush and pnpm which supports node 12 and 14

Tested rush install and rush build on Node 10, 12 and 14

Seems to be an issue with node 13 in the PR validation build(nodejs/node#31029). It also seems like there is 3 different version of node used in the 3 piplines:

• publish.yaml: 10
• push-to-npm: 12
• verify-pull-request: 13 -> 14

[timotheeguerin]

I see here common/config/rush/shrinkwrap.yaml was in the gitignore but not in autorest.megarepo. Should pnpm-lock.yaml file be? I think it defeat the point of lock files.

[daviwil]

Looks like the azure-sdk-for-js repo checks in the pnpm-lock.yaml file, I'm not sure where the shrinkwrap file comes from

[timotheeguerin]

Not familiar with pnpm or rush but I think that used to be the old name for the same file, In the megarepo PR:

[daviwil]

Interesting, I'd say let's leave it checked in for now and we can remove it if we run into problems. CI is green so I'm going to merge this. Thanks a bunch!