V14: Fix templates not having set master template on package install

[Zeegaan]

Notes

• When installing packages like Umbraco.TheStarterKit, the templates would never have their correct master template set.
• This would also cause issues with Deploy, as when you'd send content to cloud, it would cause errors.
• This PR remedies this issue, by ordering the templates correctly, by using the new TemplateContentParserService when installing package data (this was broken using Xelements)

How to test

• Install the Umbraco.TheStarterKit NuGet package
• Run Umbraco
• Assert that 9 templates have the "master" template set.

[Migaroez]

✅ Works as expected
✅ Updated code to avoid multiple GetAwaiter().GetResult() statements in the same method.