Rename solana-wallet program to just solana (#5604)

* Rename wallet/ to cli/

* Rename the solana-wallet crate to solana-cli

* Rename solana-wallet program to solana

* cargo fmt

cli/src/config.rs

@@ -0,0 +1,49 @@
+// Wallet settings that can be configured for long-term use
+use serde_derive::{Deserialize, Serialize};
+use std::fs::{create_dir_all, File};
+use std::io::{self, Write};
+use std::path::Path;
+
+lazy_static! {
+    pub static ref CONFIG_FILE: Option<String> = {
+        dirs::home_dir().map(|mut path| {
+            path.extend(&[".config", "solana", "wallet", "config.yml"]);
+            path.to_str().unwrap().to_string()
+        })
+    };
+}
+
+#[derive(Serialize, Deserialize, Default, Debug, PartialEq)]
+pub struct Config {
+    pub url: String,
+    pub keypair: String,
+}
+
+impl Config {
+    pub fn new(url: &str, keypair: &str) -> Self {
+        Self {
+            url: url.to_string(),
+            keypair: keypair.to_string(),
+        }
+    }
+
+    pub fn load(config_file: &str) -> Result<Self, io::Error> {
+        let file = File::open(config_file.to_string())?;
+        let config = serde_yaml::from_reader(file)
+            .map_err(|err| io::Error::new(io::ErrorKind::Other, format!("{:?}", err)))?;
+        Ok(config)
+    }
+
+    pub fn save(&self, config_file: &str) -> Result<(), io::Error> {
+        let serialized = serde_yaml::to_string(self)
+            .map_err(|err| io::Error::new(io::ErrorKind::Other, format!("{:?}", err)))?;
+
+        if let Some(outdir) = Path::new(&config_file).parent() {
+            create_dir_all(outdir)?;
+        }
+        let mut file = File::create(config_file)?;
+        file.write_all(&serialized.into_bytes())?;
+
+        Ok(())
+    }
+}