Update Dev Box icon to account for scaling and size increases

[bbonaby]

Summary of the pull request

Now that the PR to add the WSL extension has been checked into Dev Home Here: microsoft/devhome#3365. As mentioned in the description we need to update the icon for the Dev Box provider so that the icon does not appear pixeled in the create environment flow.

In the create environment flow the first page is where users select the provider they want to create an environment in. In this page environment providers are listed in the Settings cards UX and on the left is an icon and on the right is the name of the provider. In the above PR I updated the size of the icons in these cards from 20 to 40px. This led me seeing that the DevBox icon is pixeled and doesn't scale.

In this PR I'm adding a higher quality asset for the Dev Box provider icon that is 256 x 256 so that it can handle being scaled.
(Reason for 256 x 256 is to allow the icon to only be scaled down and never up). See info bar in icon scaling section: https://learn.microsoft.com/en-us/windows/apps/design/style/iconography/app-icon-construction#icon-scaling

Before this change:

After this change:

References and relevant issues

Detailed description of the pull request / Additional comments

Validation steps performed

confirmed icon is now not pixelated and is still showing up in the environments page.

PR checklist

• Closes #xxx
• Tests added/passed
• Documentation updated