Use scheme-specific link in Companion Information dialog

[ewpatton]

Describe the bug

The Companion Information dialog on ai2 uses an HTTP link for the companion download, even if the page itself is served over HTTPS. In particular, this is problematic because Chrome will not allow the user to download a file using an HTTP link when the host page is served over HTTPS. We should have the link's scheme reflect the page scheme.

Affects

• Designer
• Blocks editor
• Projects Explorer
• Companion
• Compiled apps
• Buildserver
• Debugging
• Other... (please describe)

Expected behavior

Clicking the link should trigger the download.

Steps to reproduce

1. Open ai2 in Chrome
2. Go to Help > Companion Information
3. Click on the link for the companion app, it will not trigger a download
4. If you edit the href in the dev tools to be HTTPS, the download link will work