Unexpected key `ContributorInsightsSpecification`

Dynamodb support `ContributorInsightsSpecification`options. The options used to enable or disable CloudWatch Contributor Insights.

When running `serverless offline start`, the following error occurs.

```

MultipleValidationErrors: There were 4 validation errors:
* UnexpectedParameter: Unexpected key 'ContributorInsightsSpecification' found in params.GlobalSecondaryIndexes[0]
* UnexpectedParameter: Unexpected key 'ContributorInsightsSpecification' found in params.GlobalSecondaryIndexes[1]
* UnexpectedParameter: Unexpected key 'ContributorInsightsSpecification' found in params.GlobalSecondaryIndexes[2]
* UnexpectedParameter: Unexpected key 'ContributorInsightsSpecification' found in params: DynamoDB - Error -
```

If `ContributorInsightsSpecification` option is declared in `Table Properties` and `GlobalSecondaryIndexes`, you should ignore it.

Start by tracing how DynamoDB Table Properties and GlobalSecondaryIndexes are handled during `serverless offline start`. Reproduce the validation error with `ContributorInsightsSpecification` in both locations, then verify that the option is ignored and offline startup completes without the unexpected-key errors.

Written by the indexing model from the issue text.