Support "Menlo" font for code snippets.

[owilliams320]

Is your feature request related to a problem? Please describe. Use the menlo font as provided by the Covalent Design spec for components coded text.

Describe the solution you'd like

1. Add a coded font token in @covalent/tokens using the "Menlo" font;
2. Use the new font token within the code snippet web component.