Originally when popping in, the ReplayPlayer was loaded first (if previous screen was MainMenu), and afterwards the SkinEditor component was loaded asynchronously. However, if the ReplayPlayer screen exits quickly (like in the event the beatmap has no objects), the skin editor component has not finished initializing (this is before it was even added to the component tree, so it's still not marked `Visible`), then the screen exiting will cause `OsuGame` to call SetTarget(newScreen) -> setTarget(...) which sees that the cached `skinEditor` is not visible yet, and hides/nulls the field. This is the point where LoadComponentAsync(editor, ...) finishes, and the callback sees that the cached skinEditor field is now different (null) than the one that was loaded, and never adds it to the component tree. This occurrence is unhandled and as such the SkinEditorOverlay never hides itself, consuming all input infinitely.

This PR changes the loading to start loading the ReplayPlayer *after* the SkinEditor has been loaded and added to the component tree.
Additionally, this lowers the exit delay for ReplayPlayer and changes the "no hit objects" notification to not be an error since it's a controlled exit.

If the SkinEditor was created already but not finished initializing, wait for it to initialize before handling a screen change, which could possibly null the skin editor. Additionally, in the case the skin editor is already loaded but hidden, make sure to show gameplay.