Add ESM typescript support to plugins via loaders.

[mshima]

Is your feature request related to a problem? Please describe.
Typescript plugins support in esm projects support is not trivial.
It's needed to add a environment variable to force node to load the typescript loader.

• Environment variables requires cross-env to be portable
• When there are lots of scripts, the section will be bloated
• npx ng ... doesn't work

Describe the solution you'd like
Add a configuration to load side effects before loading plugins:

{
  "import": "jiti/register",
  "plugins": ["./plugins/a.ts"]
}

Describe alternatives you've considered

{
  "plugins": [{ "path": "jiti/register", "sideEffect":  true }]
}

Additional context
Add any other context or screenshots about the feature request here.