Add block characters typical of terminal monospace fonts

[davelab6]

During an internal bug bash, I found an internal user wrote:

On ChromiumOS, the Cousine font family is used as the system monospaced font by default, but it appears to be missing certain block characters. This causes misalignment when using text in applications.

For example, using Mosh with Cousine breaks text-mode programs in the terminal. In particular, I've noticed misalignment occur with the BLACK RIGHT-POINTING SMALL TRIANGLE character (▸ and ▸). This character is part of the Geometric Shapes Unicode block and should probably be supported if Cousine is intended for use as a monospaced font.

Eg, when Mosh is rendering some code, the ▸ character is introduced near the beginning of some lines, falls back, and so the text becomes misaligned.

https://fonts.google.com/specimen/Cousine?preview.text=%E2%96%B8 indeed shows tofu for that character.

I expect it might be easy to add these using the scripts that Adobe Fonts folks developed for Source Code Pro, and so rebuild Cousine to include the block characters typical of terminal monospace fonts.

Of course, changing the ChromiumOS system monospace family to Roboto Mono might also make more sense...

@chrissimpkins wdyt?