Ports command line argument handling for proxy and handler to Rust

[serra-fastly]

This change is a part of the transition from C++ to Rust.

Argument handling has been collapsed into core/[handler/proxy]argsdata.cpp and core/[handler/proxy]cliargs.rs for C++ and Rust respectively. Old argument parsing logic was removed from the C++ modules. Runner was updated with the new command line values to standardize tags. ArgsData in Runner was updated to RunnerArgsData for differentiation.

In the Rust modules, handler and proxy use clap to parse arguments into CliArgs, convert to its FFI struct equivalent [Handler/Proxy]CliArgsFfi, and then call handler_main and proxy_main respectively with the [Handler/Proxy]CliArgsFfi variable being passed in as the argument. cbindgen creates a binding for [Handler/Proxy]CliArgsFfi within "rust/bindings.h" for use by C++ at compilation time. Then in the C++ modules, the [Handler/Proxy]CliArgsFfi gets loaded into an ArgsData struct for use with QT types and loaded into the Settings struct.

cbindgen was used to pass the data through because the linker had trouble with cxx due to QT (that wasn't able to be resolved with cxx-qt), but it'll be good to use cxx in the future for security and stability to create safe bindings (vs the unsafe bindings from cbindgen).

I've created unit testing for both the Rust modules that send the arguments within cliargs.rs and the C++ modules that receive the modules within [handler/proxy]argstest.cpp. Both test with the same values and the same two use cases— all arguments are set and no arguments are set.

Tested on a canary node (lck) on 08/08/2025.

[deg4uss3r]

PR looks good! Minus one debugging statement left in I think this is ready to test on a node for correctness.

[deg4uss3r]

Everything here looks good to me, going to tag in Justin though for a more thorough review of the c++ pieces.