fix: Fixes schedule:list command to take environment constraints into consideration

[nikolicaleksa]

Currently the schedule:list command lists ALL scheduled tasks, regardless if some task is limited to specific environments.

For example, if a user has defined a task that cleans up the data on a test environment, and then checks schedule:list on production, he might think that it would be executed on production as well because it would be listed there with information when the next execution is due.

This can cause confusion / panic so this fix changes the command behaviour so that it only lists tasks which apply to the current environment (unless --all option is used).

[taylorotwell]

There isn't really a fail-safe way to filter this list because any event could have a when callback that has arbitrary constraints, even on environment.

[nikolicaleksa]

@taylorotwell I was thinking if I should include when in filtering out, but as you said - people can put weird stuff in there. In any case, i think that filtering by environment is still better then doing no filtering at all. This way, at least basic case of environment is covered so I don't see why this should not be done. Can you clarify?