In order to make this possible, I've added a new `sync()` method to the
Shellable protocol, which now should allow us to run shell commands
synchronously. Back to basics, as this was how *all* commands were
run in legacy versions of PHP Monitor.
The advantage here is that there is now a choice. Previously, you'd
have to use the `system()` helper that I added.
Usage of that helper is now discouraged, as is the synchronous
shell method, but it may be useful for some methods where waiting
for the outcome of the output is required.
(Important: the `system()` helper is still required when determining
what the preferred terminal is during the initialization of the
`Paths` class.)
The older version (8.2 in most cases) that becomes obsolete will also
be reinstalled and the app will attempt to switch to the last active
version as well. It is likely that PHP Monitor will have to repair
your older PHP installations after upgrading the `php` formula, but
this too should be a seamless process.
There was an issue where updating a configuration file (including .ini)
or having an action occur that marked PHP Monitor as busy would prevent
the icon from updating correctly. This happened because access to the
busy boolean state variable could happen from various threads.
Since adding main thread isolation to the variable, you must access
`PhpEnvironments.shared.isBusy` via the main thread, therefore ensuring
that the busy state that is read from the app is always synchronized
and accurate whenever it is checked, making it so that going from
busy to no longer busy can no longer fail.
(It was possible for work in another thread to complete and fail to set
the icon to "not busy" because the work was done faster than the icon
could be set to busy.)
