ember try:reset with workspaces

[BarryThePenguin]

I've tried running ember try:reset within a monorepo with yarn workspaces and I'm seeing the following error

TypeError: Cannot read property 'map' of undefined
/node_modules/ember-try/lib/dependency-manager-adapters/workspace.js:90:43
/node_modules/ember-try/lib/utils/scenario-manager.js:40:25
...

It looks like this._packageAdapters is undefined?

ember-try/lib/dependency-manager-adapters/workspace.js

Lines 88 to 90 in aa4e3ff

	cleanup() {
	return RSVP.all(this._packageAdapters.map(adapter => adapter.cleanup()));
	},

It looks like the package adapters are initialised in setup()

ember-try/lib/dependency-manager-adapters/workspace.js

Lines 52 to 60 in aa4e3ff

	this._packageAdapters = workspacePaths.map(workspacePath => {
	return new NpmAdapter({
	cwd: workspacePath,
	run: this.run,
	managerOptions: this.managerOptions,
	useYarnCommand: true,
	buildManagerOptions: this.buildManagerOptions,
	});
	});

In the tests setup() is run before cleanup(), so either the tests are assuming setup() is run first and it isn't, or the package adapters should be initialised in both setup() and cleanup()?

ember-try/test/dependency-manager-adapters/workspace-adapter-test.js

Lines 210 to 219 in aa4e3ff

	return workspaceAdapter.setup().then(() => {
	writeJSONFile('packages/test/package.json', { originalPackageJSON: false });
	writeJSONFile('packages/test/node_modules/prove-it.json', { originalNodeModules: true });
	return workspaceAdapter.cleanup();
	}).then(() => {
	assertFileContainsJSON(path.join(tmpdir, 'packages/test/package.json'), { originalPackageJSON: true });
	assertFileContainsJSON(path.join(tmpdir, 'packages/test/node_modules/prove-it.json'), { originalNodeModules: true });
	});
	});

I can put together a PR, but I'm still figuring out what order things run in..

[rwjblue]

Should be fixed by #467