Add aoc crate that reads file from input argument; use it in the day01 crate

2022/aoc/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "aoc"
+version = "0.1.0"

2022/aoc/Cargo.toml

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+[package]
+name = "aoc"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

2022/aoc/src/lib.rs

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+use std::{env, fs};
+
+pub fn read_input_file_to_string() -> String {
+    let args: Vec<String> = env::args().collect();
+    let filename = args.get(1).expect("Missing filename argument");
+    fs::read_to_string(&filename).expect("Unable to read file")
+}
+