[lldb] Pass Wasm runtime-args before the port argument (#220700)

A runtime that dispatches on a leading subcommand, such as WasmKit's
`wasmkit run`, could not be driven directly: runtime-args landed after
the port argument, so the subcommand did too and the runtime rejected
it. Naming the subcommand required a wrapper script. Move runtime-args
ahead of the port argument so the setting can carry it.

Extract the command line assembly into PlatformWasm::MakeRuntimeCommand
so the ordering is covered by unit tests, and clarify that port-arg has
to carry its value in the same argument.

GitOrigin-RevId: 32e83eafa73dbdd8edd113de787e2819ea049357