Rename UniquelyIdentifyRunningInstance

[timbussmann]

I think the API is misleading and hard to really understand. Also it kinda conflicts with MakeInstanceUniquelyAddressable. Also it's weird to use as UniquelyIdentifyRunningInstance takes no parameter but returns a configuration class which contains different properties where

• HostInfoSettings.UsingInstalledFilePath, HostInfoSettings.UsingCustomIdentifier and HostInfoSettings.UsingNames configure the same header value
• HostInfoSettings.UsingCustomDisplayName configures a different header value.

During the acceptance test reviews we concluded that the host headers are essentially diagnostics data. I think this would be a much more suitable API category, e.g. something like:

endpointConfiguration.Diagnostics(settings => 
{
    settings.CustomDisplayName = "whatever";
    settings.HostId = HostId.Guid(Guid.NewGuid()); // HostId.FromString(endpoint, instance, ...);
});

[andreasohlund]

@timbussmann since we hopefully will move in the direction of a explicit host config api should we consider closing this?

[andreasohlund]

Bumping to the Future milestone for now, since https://github.com/Particular/NServiceBus/pull/4952 will likely make this a non issue so no need to churn the API in v7