Removal of multiple transports from TPD in a single request

[0pcom]

When a skywire visor is shut down with a lot of transports, the process is stopped before all the transports can be removed from transport discovery. This leads to a situation where TPD shows that the visor has transports that it no longer has.

In order to address this, we should make the visor able to send a single request to deregister all the transports it has from TPD ; and as well we need to make TPD able to handle such batched requests for deleting multiple transports at once.