Fix :log-open when --log is specified

[alevinval]

The command always opened the default log file path. The path can be customized passing the --log optional argument. When this is the case the open-log command should respect it.

[pascalkuthe]

thanks!

[the-mikedavis]

I think we should use the same strategy as the config file so we don't need to tote around this log_file parameter on more structs and constructors:

helix/helix-loader/src/lib.rs

Lines 12 to 27 in 618620b

	static CONFIG_FILE: once_cell::sync::OnceCell<PathBuf> = once_cell::sync::OnceCell::new();
	pub fn initialize_config_file(specified_file: Option<PathBuf>) {
	let config_file = specified_file.unwrap_or_else(|| {
	let config_dir = config_dir();
	if !config_dir.exists() {
	std::fs::create_dir_all(&config_dir).ok();
	}
	config_dir.join("config.toml")
	});
	// We should only initialize this value once.
	CONFIG_FILE.set(config_file).ok();
	}

helix/helix-loader/src/lib.rs

Lines 124 to 129 in 618620b

	pub fn config_file() -> PathBuf {
	CONFIG_FILE
	.get()
	.map(|path| path.to_path_buf())
	.unwrap_or_else(|| config_dir().join("config.toml"))
	}

[alevinval]

@the-mikedavis really nice! much cleaner, I've also done some boy-scouting around that code, let me know if you are cool with it.

[the-mikedavis]

I believe we also need an ensure_log_dir since that may be in a different directory than config (by deafult it is for example). I think it would be fine for those functions to be called in the initialize_ functions since those are only meant to be called once at initialization anyways

[alevinval]

I was about to write the following here (and the equivalent for the config_file())

unwrap_or_else(|| {
   initialize_log_file(None)
   log_file()
})

But then I really think we should unwrap() and potentially fail. A failure here means we have seriously broken the initialization steps in the main.rs, it seems less misleading than re-replicating the initialization of the cell in two places.