Ensured missing values for optional fields do not throw an error

[jsoverson]

Fixes #378

[fawadasaurus]

@jsoverson I am still getting the same error. I am not passing groups_claim at all from the app.wick.

2023-07-18T21:03:20 ERROR trigger{kind=HTTP}: trigger failed to start: Configuration provided for component '/Users/fshaikh/Developer/candlecorp/wick-components/components/oauth/oauth-mssql.wick' does not match expected signature, missing field: groups_claim

component:
  kind: wick/component/composite@v1
  with:
    - name: auth_endpoint
      type: string
    - name: token_endpoint
      type: string
    - name: redirect_uri
      type: string
    - name: session_cookie_name
      type: string
    - name: client_id
      type: string
    - name: client_secret
      type: string
    - name: scope
      type: string
    - name: db_url
      type: string
    - name: email_claim
      type: string
    - name: groups_claim
      type: string?
      ```

[jsoverson]

The liquid config is suboptimal. This PR would help if it lands: cobalt-org/liquid-rust#496