Add SentryOptions.DisableSentryHttpMessageHandler

[jamescrosswell]

Addresses the duplicate trace problem described in #3843:

• Requests proxied via YARP are missing in the traces #3843 (comment)

Essentially we allow SDK users to disable the SentryHttpMessageHandler if they are already using the OpenTelemetry.Instrumentation.Http package to trace outbound requests... to avoid duplicate instrumentation.

This PR does not address any issues around YARP - that would require separate exploration.

[bruno-garcia]

Can we flip this to false automagically if OpenTelemetry.Instrumentation.Http is installed? If so, do we need a public options or would internal with InternalsVisibleTo be enough?

[github-actions]

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