Added a bunch of comments for MigrationTaskInjector,MigrationReportPacker, RecallTaskInjector and DataFifo

Thus, The real reporters do not inherit publicly from it => Changed all the lines of coded that had to be changed

Compute it on DiskWriteTask and report it to the Client. Tests and interfaces have changed consequently

Changed consequently the types to use the interface instead of the derived type : RecallReportPacker

ReportEndofSession(WithErrors)::goingToEnd returns now true as it should and RecallReportPacker.M-terminate has been removed by goingToEnd+break if true

Moved all files related to Client to client/, changed the namespace and fixed the files consequently (header,usings,...)

log, client interface and m_listReports are now inherited from the base class

We are now using the matching files and classes frpm castor/tape/threading