feat: default inventory and manifest files for devnets

[jelias2]

Description

• Add default-alphanet, default-betanet and default-rust manifest and inventory templates.
• These can be used to initialize a devnet using `just create-devnet <alphanets/betanets>

  Example: just create-devnet alphanets holocene-test-4 default-reth
  Example: just create-devnet betanets holocene-test-4 default-betanets

  This will create a new directory in the approraite folder and copy in the templates.

  This allows for reusable inventory configurations across devnets, instead of copy and pasting existing manifests and inventories from old devnets

  This also adds kona rpc-2 and kona synctest-2 to the default alpha and betanet inventories

  Tests

  Additional context

  Metadata

[scharissis]

Cool idea.
Would prefer this in Go instead of bash for maintainability but this is better than not having it! :)

[jelias2]

Yeah I think go could be better, however if we want this to be create devnets command reusable in other contexts, the trade off would be adding go.mod, building go binary and copying the source code file into other places, which might be a bit heavy for this scenario.

If theres more logic that is added I definitely think a go implementation could make sense