main: Move VmParams creation into a dedicated function

This brings more modularity to the code, which will be helpful when we
will later test the CLI and OpenAPI generate the same VmConfig output.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vmm/Cargo.toml

@@ -12,6 +12,7 @@ mmio_support = ["vm-virtio/mmio_support"]
 cmos = ["devices/cmos"]
 
 [dependencies]
+clap = "2.33.0"
 acpi_tables = { path = "../acpi_tables", optional = true }
 anyhow = "1.0"
 arch = { path = "../arch" }