Use generated groups, and publish/subscribe from a task, in the Julia examples

[tsaubergine]

Two changes to the Julia examples. The second needs GobySoft/goby3#413.

Name groups through the generated module

goby_add_julia_app() writes a module beside each application with a constant per group and an accessor per portal, but the examples still repeated the interface.yml expression as a string:

Goby.publish(app, Goby.INTERPROCESS, "groups::julia_nav", nav)

They now include that module and name the group through it:

include(joinpath(@__DIR__, "basic_julia_publisher_goby.jl"))
using .BasicJuliaPublisherGoby: groups, interprocess

Goby.publish(app, interprocess(), groups.julia_nav, nav)

The expression then lives in one place, and a mistyped group is an UndefVarError naming it rather than a GOBY_JULIA_FAIL that terminates the application once the publish is reached.

Publish and subscribe from a task in the multithread example

The example was written when INTERPROCESS was reachable only from Main, and its header said so — publishing from a task raised an AssertionError. With GobySoft/goby3#413 that is no longer true, so the example now shows what the layer actually offers:

• the subscriber task publishes deep reports to INTERPROCESS itself, rather than handing them to Main over INTERTHREAD
• the publisher task subscribes to the same group from its own thread

Main keeps the INTERTHREAD depth-alert subscription, which is still where the "an interthread message can be any Julia value" point lives (the alert is a NamedTuple). interface.yml gains the matching subscribes entry.

Verified against a live gobyd: each deep report reaches both the separate basic_julia_subscriber process and the publisher task, exactly once.

[publisher] Tx: z=-300.1
[subscriber] Rx: z=-300.1
[main] alert: 300.1 m at x=98.2 y=213.1
[publisher] on the wire: z=-300.1

The publisher/subscriber pair was re-run too, to check the generated-module change on its own.

Note on CI

This job installs libgoby3-dev and goby3-julia from the continuous package repo and only builds, so its green proves the Julia examples compile — including the new subscribes entry generating valid C++ — not that the multithread example runs. That needs #413 merged and the continuous package rebuilt; the runtime evidence above is from a local build of that branch.