Mermaid chart integration

[truongdo]

It would be great to have mermaid integrated with outline. It's a great chart and diagram visualization using markdown definitions.

https://github.com/mermaid-js/mermaid

[BRogers80]

Yes,please. +1

[kengjungwa]

+1 too.
It'd be very convenient and seamless to be able to edit mermaid diagrams within Outline as we do our design documentation.

[Shide]

PR: #3523
Transferred to #3679

[tommoor]

As part of this work I just reduced the size of mermaidjs for everyone by 8% 😆

mermaid-js/mermaid#3167