Install fonts from xml2rfc-fonts repository

[kesara]

Description

In order to generate internet draft PDFs with correct fonts, use fonts from xml2rfc-fonts font repository.

Code of Conduct

• I agree to follow the IETF's Code of Conduct

[larseggert]

Might want to add https://fonts.google.com/noto/specimen/Noto+Emoji to xml2rfc-fonts, due to #6050.

[kesara]

Might want to add https://fonts.google.com/noto/specimen/Noto+Emoji to xml2rfc-fonts, due to #6050.

It is a separate project, I created ietf-tools/xml2rfc-fonts#1 to add emoji fonts from Noto Emoji Project.