[Thread] add Thread icon

This is imported from material icon at https://fonts.corp.google.com/icons?selected=Google%20Symbols%3Athread_logo%3AFILL%400%3Bwght%40400%3BGRAD%400%3Bopsz%4024

But system notifications and settings also need to use this icon. For
example, it will be used in Settings > Connected devices > Connection preferences.

Bug: 327583301
Change-Id: I08ef9c90b7d4085f9b901b3d9c41b57258aa9680