[UX] Project installer: Clarify reason that the server does not support automatic updates

Description of the need

Right now, if you visit the Update Modules page and backdrop doesn't have permission to change the site files, the message says:

Your server does not support updating modules, themes, and layouts from this interface. Instead, update modules, themes, and layouts by uploading the new versions directly to the server, as described in the handbook.

This message omits the option of just changing the file permissions on the server, rather than giving up on automatic updates and doing things manually.

Proposed solution

Change the text to say:

Your server configuration does not support updating modules, themes, and layouts from this interface. You can either change file permissions to let backdrop edit the code in its own directory, or manually upload new versions of modules, themes, and layouts directly to the server, as described in the handbook.

Or alternative wording:

Your server configuration does not support updating modules, themes, and layouts from this interface. If you are unable to change file permissions to let backdrop edit the code in its own directory, you should manually upload new versions of modules, themes, and layouts directly to the server, as described in the handbook.