Fix: Usage of Simu5G components inside compound modules

[Dosclic98]

These changes aim to fix some errors found when using the Simu5G components inside compound modules. In the original version, there were some issues when trying to find the specified module using just the getFullName() method instead of the getFullPath(). Changed this behavior in the GptUser, TrafficFlowFilter (where I also added some code to free the allocated memory at the end of the simulation) and in the LteMacEnb modules.

Now for all the gnbs the value of the parameter gateway must be specified using the full path of the gateway module as in the following example (we suppose that the top level network is called 'Network'): Before **.gnb.gateway = "upf" Now: **.gnb.gateway = "Network.upf"

I dont't know if it is better to let the user specify it every time or implement some code that adds the network name at runtime when the gateway name specified implicitly refer to the top level (like the first one).

[giovanninardini]

Added a commit that:

• fixes compatibility with existing simulations and merged with the master branch.
• make it not necessary to put the name of the top-level module of the network in the gateway parameter. So, **.gnb.gateway = "upf" works as expected