connman: build with iwd support

[rookiejet]

Testing the changes

• I tested the changes in this PR: YES

Allows using iwd instead of wpa_supplicant for wireless connections.

[cinerea0]

Does this mean the explicit dependency on wpa_supplicant should be removed, and backends listed in a README.voidlinux file?

[rookiejet]

Yes, wpa_supplicant is an optional dependency. Per the src readme it's not required during build time to enable support for it in connman, it's only a runtime dependency.

Edit: Amended

[ahesford]

Removing wpa_supplicant may break some users' installations if they remove orphans. I think the dependency should be kept for now and an INSTALL.msg should be added for a couple of release cycles to note that the dependency will be removed in the future and that users relying on it should mark wpa_supplicant manually installed.

[rookiejet]

That's reasonable. wpa_supplicant is actually a dependency of base-system as well, so it won't be orphaned and uninstalled if it is removed from here. Would that suffice for this merge?

[ahesford]

Not everybody uses base-system, so relying on its dependencies to not break connman is insufficient.

[rookiejet]

I revised the commit with @ahesford's recommendation, and included an INSTALL.msg