#[blvm_module]Expand description
Attribute macro: #[blvm_module] - marks the main module struct.
On struct: #[module(name = "demo", config = DemoConfig)] generates __module_new(config).
With migrations = ((1, up_initial), (2, up_add_items_tree)) also generates ModuleMeta impl
for run_module_main!(DemoModule).
On impl: #[module(name = "demo")] generates cli_spec, dispatch_cli, rpc_method_names, etc.