Only add a new node if the current number of connected nodes is below the max
Define "first party networks" to be: Polkadot, Kusama, Westend and Rococo. All other networks are capped to 500 nodes
* working backend on docker
refactor of the dockerfiles to be more readable and independent.
full build of the backend (release only) within docker
* read `PORT` to u16
* Only need one `PORT` in the new backend
Co-authored-by: Maciej Hirsz <1096222+maciejhirsz@users.noreply.github.com>