Allow the user to specify his/her own ports

[Ivansete-status]

Now we have the ports hard-coded. It is interesting to give the user the possibility to specify the desired ports, and use the current ones as the default values, for example.

Note: this issue was originally generated by @jakubgs in Waku Workshop session - https://notes.status.im/tB2E-WXVTECCD7Ni-LDERQ?view