macros: support setting name of spawned threads

[cgzones]

Support setting the names of spawned tokio threads.

[Darksonn]

We don't add all of the runtime options to the main macro. This option seems rather specialized. You can set it through the runtime builder if you require specialized configurations.

[cgzones]

I'd like to set the name manually to avoid comm=tokio-runtime-w in audit events, which is not clear on the first sight from what application it originates.