Add validateApiDoc props in OpenApiValidatorOpts

[ZhouJian26]

Hi, i added validateApiDoc props in OpenApiValidatorOpts interface. I noticed that it was missing, watching these few lines:

express-openapi-validator/src/framework/index.ts

Lines 34 to 54 in e57e04e

	const validateApiDoc =
	'validateApiDoc' in args ? !!args.validateApiDoc : true;
	const validator = new OpenAPISchemaValidator({
	version: apiDoc.openapi,
	// extensions: this.apiDoc[`x-${args.name}-schema-extension`],
	});
	if (validateApiDoc) {
	const apiDocValidation = validator.validate(apiDoc);
	if (apiDocValidation.errors.length) {
	console.error(`${this.loggingPrefix}Validating schema`);
	console.error(
	`${this.loggingPrefix}validation errors`,
	JSON.stringify(apiDocValidation.errors, null, ' '),
	);
	throw new Error(
	`${this.loggingPrefix}args.apiDoc was invalid. See the output.`,
	);
	}
	}

Now it is possible to disable the OpenAPI specification validation.

app.use(
  OpenApiValidator.middleware({
    apiSpec: './openapi.yaml',
    validateApiDoc: false // true by default
  }),
);

[cdimascio]

thanks @ZhouJian26!
i modified this some to rename the new option to validateApiSpec for consistency with the apiSpec option