Design: Update Dialog component to include line for info text below buttons

[cathystoli]

Additionally include "footer" section in master SDS library for use by CZ GE.

Link to Figma file with example:

https://www.figma.com/file/eUo8Lb0fMCct0YuPmRDQ3n/GISAID-Terms-of-Use?node-id=40%3A4495