Feature request: add custom url chat links

[asouppart]

add custom url chat links, for open directly chat session with specific person
by exemple : https://matrix.to/#/@moi:matrix.mondomaine.fr

[coudot]

Some questions on this request:

• the @moi is a value that we can found in some LDAP attribute (uid, mail, ...)?
• the matrix.mondomaine.fr is common to all users from the directory? If not, is this value in an attribute of the user?
• Do you prefer to display the link as a value like any other attribute, or do we create an action button, like we have for the vCard ?