chore: migrate fully to Yarn (#3155)

* chore: migrate to Yarn package manager

* chore: bump deps, move `expose-loader` to correct deps section

* fix: remove package from old typescript shim

* feat: use Yarn Plug'n'Play

* chore: keep `node_modules` ignored for people who choose to use npm anyway

* Revert "feat: use Yarn Plug'n'Play"

This reverts commit 9781c8c8d5.

js/.gitignore

@@ -0,0 +1,9 @@
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/sdks
+!.yarn/versions
+
+node_modules