Move schedule name into Schedule

[hymm]

Objective

• Move schedule name into Schedule to allow the schedule name to be used for errors and tracing in Schedule methods
• Fixes Schedule build errors should include the schedule in which the problem occurred when reporting problems bevyengine/bevy#9510

Solution

• Move label onto Schedule and adjust api's on World and Schedule to not pass explicit label where it makes sense to.
• add name to errors and tracing.
• Schedule::new now takes a label so either add the label or use Schedule::default which uses a default label. default is mostly used in doc examples and tests.

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Changelog

• move label onto Schedule to improve error message and logging for schedules.

Migration Guide

Schedule::new and App::add_schedule

// old
let schedule = Schedule::new();
app.add_schedule(MyLabel, schedule);

// new
let schedule = Schedule::new(MyLabel);
app.add_schedule(schedule);

if you aren't using a label and are using the schedule struct directly you can use the default constructor.

// old
let schedule = Schedule::new();
schedule.run(world);

// new
let schedule = Schedule::default();
schedule.run(world);

Schedules:insert

// old
let schedule = Schedule::new();
schedules.insert(MyLabel, schedule);

// new
let schedule = Schedule::new(MyLabel);
schedules.insert(schedule);

World::add_schedule

// old
let schedule = Schedule::new();
world.add_schedule(MyLabel, schedule);

// new
let schedule = Schedule::new(MyLabel);
world.add_schedule(schedule);