Support `node:process/fs` syntax

[radu-matei]

The readme currently states:

Note: this currently does not support the node:process syntax yet.

Validating that if I try using the syntax today I get a build error:

❯ spin build
Building component wasi-ext-tests with `npm run build`

> test-app@1.0.0 build
> npx webpack && mkdirp dist && j2w -i build/bundle.js -n test -o dist/wasi-ext-tests.wasm

ERROR in node:process
Module build failed: UnhandledSchemeError: Reading from "node:process" is not handled by plugins (Unhandled scheme).
Webpack supports "data:" and "file:" URIs by default.
You may need an additional plugin to handle "node:" URIs.
    at /Users/radu/projects/src/github.com/fermyon/js-wasi-ext/tests/test-app/node_modules/webpack/lib/NormalModule.js:984:10
    at Hook.eval [as callAsync] (eval at create (/Users/radu/projects/src/github.com/fermyon/js-wasi-ext/tests/test-app/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:6:1)
    at Hook.CALL_ASYNC_DELEGATE [as _callAsync] (/Users/radu/projects/src/github.com/fermyon/js-wasi-ext/tests/test-app/node_modules/tapable/lib/Hook.js:18:14)
    at Object.processResource (/Users/radu/projects/src/github.com/fermyon/js-wasi-ext/tests/test-app/node_modules/webpack/lib/NormalModule.js:980:8)
    at processResource (/Users/radu/projects/src/github.com/fermyon/js-wasi-ext/tests/test-app/node_modules/loader-runner/lib/LoaderRunner.js:220:11)
    at iteratePitchingLoaders (/Users/radu/projects/src/github.com/fermyon/js-wasi-ext/tests/test-app/node_modules/loader-runner/lib/LoaderRunner.js:171:10)
    at runLoaders (/Users/radu/projects/src/github.com/fermyon/js-wasi-ext/tests/test-app/node_modules/loader-runner/lib/LoaderRunner.js:398:2)
    at NormalModule._doBuild (/Users/radu/projects/src/github.com/fermyon/js-wasi-ext/tests/test-app/node_modules/webpack/lib/NormalModule.js:965:3)
    at NormalModule.build (/Users/radu/projects/src/github.com/fermyon/js-wasi-ext/tests/test-app/node_modules/webpack/lib/NormalModule.js:1155:15)
    at /Users/radu/projects/src/github.com/fermyon/js-wasi-ext/tests/test-app/node_modules/webpack/lib/Compilation.js:1422:12
 @ ./src/index.ts 3:0-35 41:26-37

webpack compiled with 1 error
Error: Build command for component wasi-ext-tests failed with status Exited(1)