BREAKING: DENO_FUTURE=1 by default, or welcome to Deno 2.0 (#25213)

This commit effectively turns Deno into Deno 2.0.

This is done by forcing `DENO_FUTURE=1` env var, that was available in
the past few months to try Deno 2 changes.

This commit contains several breaking changes scheduled for Deno 2:
- all deprecated JavaScript APIs are not available any more, mostly
`Deno.*` APIs
- `window` global is removed
- FFI, WebGPU and FS APIs are now stable and don't require
`--unstable-*` flags
- import assertions are no longer supported
- "bring your own node modules" is enabled by default

This is the first commit in a series that are scheduled before the Deno
2 release.

Follow up work is tracked in
https://github.com/denoland/deno/issues/25241.

---------

Co-authored-by: Asher Gomez <ashersaupingomez@gmail.com>
Co-authored-by: Nayeem Rahman <nayeemrmn99@gmail.com>
Co-authored-by: Nathan Whitaker <nathan@deno.com>

tests/specs/npm/local_dir_no_duplicate_resolution/deno.json

@@ -1,5 +1,5 @@
 {
-  "nodeModulesDir": true,
+  "nodeModules": "local-auto",
   "imports": {
     "preact": "npm:preact",
     "preact-render-to-string": "npm:preact-render-to-string"