feat: Add audio/local to device capabilities

Spotify Connect does not allow you to move playback of a local file to
the librespot device as it says that it "can't play this track". Note
that this is slightly inconsistent as Spotify allows you to switch to
a local file if librespot is already playing a non-local file, which
currently fails with an error.

However, it is possible for the desktop and iOS client to accept
playback of local files. In looking at the PUT request sent to
`connect-state/v1/devices/<id>` from the iOS client, it can be seen that
it includes `audio/local` as an entry in the `supported_types`
capability field.

This commit introduces this field to the capabilities that librespot
sends. For now, it is a complete lie as we do not support local file
playback, but it will make the ongoing development of this feature
easier, as we will not have to queue up a non-local track and attempt
to switch to a local one.

Testing shows that with this flag the "can't play this track" message
disappears and allows librespot to (attempt) to play a local file
before erroring out.

CHANGELOG.md

@@ -70,12 +70,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - [connect] Add `pause` parameter to `Spirc::disconnect` method (breaking)
 - [connect] Add `volume_steps` to `ConnectConfig` (breaking)
 - [connect] Add and enforce rustdoc
+- [connect] Add `audio/local` to the `supported_types` field of the device capabilities.
 - [playback] Add `track` field to `PlayerEvent::RepeatChanged` (breaking)
 - [playback] Add `PlayerEvent::PositionChanged` event to notify about the current playback position
 - [core] Add `request_with_options` and `request_with_protobuf_and_options` to `SpClient`
 - [core] Add `try_get_urls` to `CdnUrl`
 - [oauth] Add `OAuthClient` and `OAuthClientBuilder` structs to achieve a more customizable login process
 
+
 ### Fixed
 
 - [test] Missing bindgen breaks crossbuild on recent runners. Now installing latest bindgen in addition.

connect/src/state.rs

@@ -161,7 +161,11 @@ impl ConnectState {
                 supports_gzip_pushes: true,
                 // todo: enable after logout handling is implemented, see spirc logout_request
                 supports_logout: false,
-                supported_types: vec!["audio/episode".into(), "audio/track".into()],
+                supported_types: vec![
+                    "audio/episode".into(),
+                    "audio/track".into(),
+                    "audio/local".into(),
+                ],
                 supports_playlist_v2: true,
                 supports_transfer_command: true,
                 supports_command_request: true,