server: use a command line parser

[vincenzopalazzo]

This commit adds a command line parser to the server. The parser is useful to avoid crashing when trying to run a simple --help command and also in the future when we will add more configuration options.

It will be really cool if the config file is optional and the user can configure the server using the command line by appending all the options to ldk-server --option1 value1 --option2 value2.

     Running `target/debug/ldk-server --help`
thread 'main' panicked at ldk-server/src/main.rs:30:56:
Invalid configuration file.: Custom { kind: NotFound, error: "Failed to read config file '--help': No such file or directory (os error 2)" }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
[1]    750067 IOT instruction (core dumped)  cargo run --bin ldk-server -- --help

[vincenzopalazzo]

I do not know if you want to keep the configuration a positional argument or it is fine introduce a --config flag

[G8XSU]

Currently we avoid clap dependency in server since we need a single argument.
We don't foresee the number of args increasing. Everything else should just be part of config.

[vincenzopalazzo]

Currently we avoid clap dependency in server since we need a single argument. We don't foresee the number of args increasing. Everything else should just be part of config.

Oh I see make a lot of sense, so I will update the PR in according with this! sorry for the miss understanding!

[vincenzopalazzo]

Ok sorry for the delay here.

I modified the code and just make a small match on the --help string. I updated the commit description too 57959aa probably I will not update the PR description otherwise the discussion did not make anymore sense for people in the future?

P.S: I rebase the PR on top of the @dzdidi PR!

[vincenzopalazzo]

While reading your suggestion on some review @G8XSU I wrote another commit to check if the config file is a file f3cee47

let me know if you prefer this solution and remove the --help, or if you want to keep both. Anything is fine for me, I preferer keep --help because I use a lot of command line and for me (and I guess many command line users) the --help is the main source of docs 😸

[G8XSU]

Lgtm! Thanks !