Extended domains with advanced configuration

[elfenpiff]

Brief feature description

Inspired by the following conversation: #616 (comment)

The iceoryx2 config folder shall contain subfolders with the domain name so that every domain can have their individual configuration.

From @elBoberido

.config/iceoryx2
  |- generic
  |- io.iceoryx2
  |- org.phantom
  |- org.phantom.opera
  |- iceoryx2.toml

A node created via NodeBuilder::new() would end up in generic and a node created via NodeBuilder::new_with_domain("org phantom.opera") would end up in that domain. One could think of moving everything to .config/iceoryx2/domains/, in case we need other, iceoryx related folders in iceoryx2. Each domain could have it's own config file. If that's not present, look at /etc/iceoryx2/domains/org.phantom.opera/iceoryx2.toml, then .config/iceoryx2/domains/iceoryx2.toml and finally /etc/iceoryx2/domains/iceoryx2.toml