Is your feature request related to a problem? Please describe.

Currently to authorize a graphql query all parameters have to be in the body of
the post request. Many tools like the grafana infinity data source
support adding authentication values via HTTP header, but do not support modifying the request body.
This makes it difficult to use them with the cloudbeaver graphql api.

Describe the solution you'd like

There are multiple ways to support authentication via headers. Two possible approaches are outlined below.

Option 1: Standard Auhtorization header

Suport using Authorization: Bearer <TOKEN> for authLogin.
The Reverse Proxy handler already apperts to support header-based authentication:

Option 2: Custom headers mapped into the credentials object

Allow custom headers to be injected into the credentials object when authenticating

Describe alternatives you've considered

Using the reverse proxy provider.

• Adds additional deployment complexity
• Weakens security by expanding the trusted surface area

Additional context

Below is an example request using Option 2, where authentication data is partially provided via HTTP headers:

echo -n 'Password123' | md5sum | tr a-z A-Z

curl http://localhost:8978/api/gql \
  -Ss \
  -X POST \
  -H "Content-Type: application/json" \
  -H "X-Cloudbeaver-user: admin123" \
  -d @- <<'EOF'
{
  "operationName": "authLogin",
  "query": "
    query authLogin($provider: ID!, $credentials: Object!, $useHeaders: Boolean) {
      auth: authLogin(provider: $provider, credentials: $credentials, useHeaders: $useHeaders) {
        userTokens {
          userId
        }
      }
      projects: listProjects{
        id
        global
        shared
        name
        description
        canEditDataSources
        canViewDataSources
        canEditResources
        canViewResources
      }
    }
  ",
  "variables": {
    "provider": "local",
    "useHeaders": true,
    "credentials": {
      "password": "42F749ADE7F9E195BF475F37A44CAFCB"
    }
  }
}
EOF