Set required parameter attribute in OpenAPI metadata

[captainsafia]

By default, OpenAPI assumes that all parameters are optional parameters.

https://swagger.io/docs/specification/describing-parameters/

We don't currently propagate any information that says required: true for parameters that are required in an endpoint

This builds on top of the work done in #32375

[davidfowl]

Turns out this requires changes in 2 places:

• We need to set the IsRequired flag on API explorer metadata
• We need to make sure consumers use this flag. Today Swashbuckle ignores this flag and determines optionality using custom logic (Change how IsRequired for parameter descriptions work domaindrivendev/Swashbuckle.AspNetCore#2183)