refactor(sdk): Remove NetworkArg + Make functions that accept Network methods of Network

[PatStiles]

Refactor Network Arg

Description

Refactors the Network struct in the sdk to:

• Derive ValueEnum and thus remove the need for NetworkArg
• Refactors functions that accept Network and return addresses to be methods of Network.

Type of change

Please delete options that are not relevant.

• Refactor

Checklist

• “Hotfix” to testnet, everything else to staging
• Linked to Github Issue
• This change depends on code or research by an external entity
  • Acknowledgements were updated to give credit
• Unit tests added
• This change requires new documentation.
  • Documentation has been added/updated.
• This change is an Optimization
  • Benchmarks added/run
• Has a known issue
  • Link to the open issue addressing it
• If your PR changes the Operator compatibility (Ex: Upgrade prover versions)
  • This PR adds compatibility for operator for both versions and do not change batcher/docs/examples
  • This PR updates batcher and docs/examples to the newer version. This requires the operator are already updated to be compatible

[MarcosNicolau]

Nice!