Fix Forest when using a config file to run calibnet

[elmattic]

Summary of changes

Changes introduced in this pull request:

• Add a proper enum for representing network chain
• Fix Forest when using toml file to run calibnet
• Disallow usage of flags --config and --chain at the same time

Reference issue to close (if applicable)

Closes

Other information and links

Related to issue we are facing in #2367 (comment)

Note the reason we need the fix on main branch is because the benchmark script is always compiling a fresh version of forest using main.

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.