New PR from #339 (The old PR closed because it's base branch has been merged & deleted)

Description

• Get schema change API - Query

  query SchemaChange {
      schemaChange {
        deletedTables
        deletedColumns
        modifiedColumns
     }
  }

• Trigger schema change API - Mutation

   mutation Mutation {
      triggerDataSourceDetection
   }

• Resolve schema change API - Mutation

   # The modified columns is not support for resolving schema changes
   enum SchemaChangeType {
     DELETED_TABLES
     DELETED_COLUMNS
     MODIFIED_COLUMNS
   }
  
   input ResolveSchemaChangeWhereInput {
     type: SchemaChangeType!
   }
  
   mutation Mutation($where: ResolveSchemaChangeWhereInput!) {
     resolveSchemaChange(where: $where)
   }