Expose YAML schema errors returned from Graphql

What does this MR do and why?

Expose YAML schema errors returned from Graphql

Updates the analytics dashboards error messages to include relevant graphql errors when the schema validation fails.

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Screenshots or screen recordings

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Missing panel title field

Before	After

Invalid / missing panel visualization field

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

Setup

• Please make sure that you have a GitLab Ultimate license
• Enable the group_analytics_dashboard_dynamic_vsd feature flag

  $ Feature.enable(:group_analytics_dashboard_dynamic_vsd)

1. Create a group or select an existing one
2. Follow the instructions to add a YAML configuration for the group, but you will need to use this example below for your schema:

   title: 'Custom Dashboard title'
   description: 'Custom description'
   panels: 
     - title: 'My Custom Project' # broken panel - missing `visualization`
       gridAttributes:
         yPos: 1
         xPos: 0
         width: 12
         height: 6
       queryOverrides:
         namespace: <path-to-project>

3. Navigate to Analyze > Analytics Dashboards in the left hand menu
4. There will be 2 dashboards available in the dashboard list (Value Streams Dashboard + Your custom YAML dashboard)
5. Select the custom dashboard
6. An error message should appear
7. Replace the dashboard configuration with this updated configuration

   title: 'Custom Dashboard title'
   description: 'Custom description'
   panels: 
     - visualization: dora_chart
       gridAttributes:
         yPos: 1
         xPos: 0
         width: 12
         height: 6
       queryOverrides:
         namespace: <path-to-project>

8. Navigate to Analyze > Analytics Dashboards in the left hand menu
9. There will be 2 dashboards available in the dashboard list (Value Streams Dashboard + Your custom YAML dashboard)
10. Select the custom dashboard
11. An error message should appear

Related to #432587 (closed)