Added more namespaces to _ViewImports.cshtml

[abjerner]

Prerequisites

• I have added steps to test this contribution in the description below

Description

Maybe I'm doing something wrong, but in new Umbraco projects, I have problems with referencen certain types from Razor views due to implicit usings, but without any errors shown in Visual Studio.

For instance, any type in the System.IO namespace will look fine in Visual Studio - e.g. as shown here:

But accessing the view will result in a Razor compile error:

Adding a @using System.IO will fix the issue, but it's a bit frustrating, as Visual Studio won't show any errors, so I often end up forgetting this until I see the error when running the site.

The same happens for the Microsoft.AspNetCore.Hosting (I use injecting IWebHostEnvironment a lot directly in the view when debugging something), which why my PR is for these to namespaces in particular. I can't remember whether I have encountered similar issues for other namespaces, but here are probably some more as well 🤷‍♂️

[github-actions]

Hi there @abjerner, thank you for this contribution! 👍

While we wait for one of the Core Collaborators team to have a look at your work, we wanted to let you know about that we have a checklist for some of the things we will consider during review:

• It's clear what problem this is solving, there's a connected issue or a description of what the changes do and how to test them
• The automated tests all pass (see "Checks" tab on this PR)
• The level of security for this contribution is the same or improved
• The level of performance for this contribution is the same or improved
• Avoids creating breaking changes; note that behavioral changes might also be perceived as breaking
• If this is a new feature, Umbraco HQ provided guidance on the implementation beforehand
• 💡 The contribution looks original and the contributor is presumably allowed to share it

Don't worry if you got something wrong. We like to think of a pull request as the start of a conversation, we're happy to provide guidance on improving your contribution.

If you realize that you might want to make some changes then you can do that by adding new commits to the branch you created for this work and pushing new commits. They should then automatically show up as updates to this pull request.

Thanks, from your friendly Umbraco GitHub bot 🤖 🙂

[emmagarland]

Hi @abjerner,

Thanks for your PR to fix the missing namespace issue you're getting!

I'm just asking if anyone else in HQ gets this issue, I can't find it in the issues list.

After that, we will review and merge (I expect if it seems that others are getting this issue).

Best wishes

Emma