Add support for multiple testnest where seed is not part of the bootstrap.

[Wayonb]

Is your feature request related to a problem? Please describe.
With more testnets getting created, the network seed and config/preset should be moved out of the bootstrap and hosted somewhere like in github.

Describe the solution you'd like
The bootstrap should pull the files required to start a network and then create the node.

[fboucquez]

Hi @Wayonb , thank you for creating the issue.

The feature has been implemented in https://github.com/symbol/symbol-bootstrap/pull/331.

A user can provide an external network.yml and seed folder. The testnet zip uses the external files, #341 was merged after creating those zips.

We could zip the current joeynet testnet into a file and push it to s3. This won't be user-friendly as the user needs to pull from s3, unzip and configure to use those external files.

I think having the 'principal' testnet bundled on bootstrap is fine. Secondary testnets (like garush) could be pushed externally if we want people to create their own nodes and connect to it.

[Wayonb]

Hi @fboucquez,
Base on discussions in discord, we want to have a single copy of network seed and base config. This will change for mainnet and testnet also.