Repurpose ID as unique publisher ID

[KerstinKeller]

Context

The publisher has a function to set an ID

ecal/ecal/core/include/ecal/ecal_publisher.h

Line 365 in 0f16b39

ECAL_API bool SetID(long long id_);

, in order to distinguish topics that are send on the same topic name, but coming from different publishers.
By default this topic id is 0.
By giving a unique default ID to the publisher, this ID can later be used e.g. to store / connect descriptor information with a given publisher, also in measurements.

Proposal

No response

Tasks and updates

Discussion points:

• Do we want to deprecate the SetId function?