HomeSoftware Heritage

mailmap: Move feature into a dedicated django application

Description

mailmap: Move feature into a dedicated django application

Move all templates, views, urls and commands related to the mailmap
feature into its dedicated django application.

Please note that the initial migration will not perform any database
operations as the tables have already been created by the swh.web.auth
django application the mailmap feature was previously located at.

Related to T4398