added code for ls exercise

Author: Luke-Manyamazi

implement-shell-tools/ls/ls.mjs

@@ -0,0 +1,24 @@
+import { program } from "commander"
+import process from "node:process"
+import { promises as fs } from "node:fs"
+import { readdir } from 'node:fs/promises'
+
+program
+    .name("ls")
+    .description("Lists the files in a directory")
+    .option("-1, --one", "One per line")
+    .option("-a", "Include files starting with dot")
+    .argument("filepath")
+program.parse(process.argv)
+
+const argv = program.args
+const opts = program.opts()
+
+if (argv.length != 1){
+    console.error("Expected 1 argument")
+    process.exit(1)
+}
+
+const content = await fs.readdir(argv[0])
+
+console.log(content.join(opts.one ? "\n": " "))