populate gossipSeeds so that they can be automatically passed as a parameter into the template

In some cases it might be necessary to create a configuration file with the well known address in it. The autoconfigure framework doesn't automatically populate the Gossip seeds so if you wanted to use them in the template you would need to do something like:

variables:
      gossipSeeds: ...

What I'm proposing is that the framework populates the seeds -if they are available- so that the user could do the following without explicitly declaring the variable as previously shown:

configuration(configuredService, ..., gossipSeeds) ::= <<
...
wka=<gossipSeeds.first.host>:<gossipSeeds.first.port>
>>

Note tha gossipSeeds has similar behavior as serviceCollections.