Before, we'd show a helpful error message when a task isn't running
instead of erroring in a generic way. Turns out when an alloc is
terminal but reachable, the filesystem is left behind so we were hiding
it.
Now it is always shown and in the event that something errors, it'll
either be generic, or--more commonly--a 404 of the allocation.
This is mostly a direct application of the ember-angle-brackets-codemod.
I manually restored newlines in multi-line component invocations, usually
preserving file line length except for now-non-positional link-to @route.
I needed to rename task to taskState in some cases to avoid Ember
Concurrency naming conflicts.
This partially addresses #7799.
Task state filesystems are contained within a subdirectory of their
parent allocation, so almost everything that existed for browsing task
state filesystems was applicable to browsing allocations, just without
the task name prepended to the path. I aimed to push this differential
handling into as few contained places as possible.
The tests also have significant overlap, so this includes an extracted
behavior to run the same tests for allocations and task states.
