Put model state into an Arc (#28)

Previously the model state was in a `static STATE` to make it accessible to all the various subsystems. This moves it into an Arc and plumbs the reference around via function arguments. That allows us to do non-static initialization, eg based on user config. I also moved some things into dioxus context.

Co-authored-by: Sam Sartor <me@samsartor.com>
Co-committed-by: Sam Sartor <me@samsartor.com>

gui/src/imp/stub.rs

@@ -1,6 +1,6 @@
 /// Stub implementation of the platform interface, so that we can
 /// `cargo check` without any --feature flags.
-use crate::effects::AudioProcessor;
+use crate::{app::SharedState, effects::AudioProcessor};
 use color_eyre::eyre::Error;
 use dioxus::hooks::UnboundedReceiver;
 use mumble_web2_common::{ProxyOverrides, ServerStatus};
@@ -25,6 +25,7 @@ impl super::PlatformInterface for StubPlatform {
         _username: String,
         _event_rx: &mut UnboundedReceiver<crate::app::Command>,
         _overrides: &ProxyOverrides,
+        _state: SharedState,
     ) -> impl Future<Output = Result<(), Error>> {
         async { panic!("stubbed platform") }
     }
@@ -77,6 +78,7 @@ impl super::AudioPlayerInterface for StubAudioPlayer {
     }
 }
 
+#[derive(Clone)]
 pub struct StubConfigSystem;
 
 impl super::ConfigSystemInterface for StubConfigSystem {