[vscode-graphql] multi project support

### Current Behavior

Autocomplete shows only `q1` as a query and gives an error on `q2`

### Expected Behavior

The readme says it supports multiple projects so autocomplete should show `q1` and `q2`

### Steps To Reproduce

Files
```yml
# graphql.config.yml
projects:
p1:
schema: s1.graphql
p2:
schema: s2.graphql
```
```graphql
# s1.graphql
type Query {
q1: Int
}
```
```graphql
# s2.graphql
type Query {
q2: Int
}
```

### Environment

* GraphiQL Version: v0.3.18
* VSCode Version: 1.81.1
* OS: Windows

### Anything else?

_No response_