VS Code extension: "aspire" launch configuration does not accept environment variables

[karolz-ms]

Repro steps

1. Create an Aspire app (any starter app is fine)
2. Open application folder in VS Code
3. Add the following launch configuration to launch.json

{
  "type": "aspire",
  "request": "launch",
  "name": "Aspire: Launch default AppHost",
  "program": "${workspaceFolder}",
  "env": {
    "FOO": "bar"
  }
}

Expected

Should work

Actual

A warning that env property is not allowed.
The environment variable is not set during application run (F5).