[FEATURE] Add URL and User_Agent Mappings

[Dan Dong]

Is your feature request related to a problem?

The AWS_ELB dashboard depends on fields contained in url schemas that the catalog does not yet have. Other integrations will have more fields that are not in existing schemas.

What solution would you like?

Adding missing schema files required for future integrations.

What alternatives have you considered?

None

Do you have any additional context?

• https://www.elastic.co/guide/en/ecs/current/ecs-user_agent.html
• https://www.elastic.co/guide/en/ecs/current/ecs-url.html

[YANGDB]

use the http mapping:

opensearch-catalog/docs/schema/observability/logs/http.md

Line 10 in b91f5ba

 | http.user_agent        | keyword |