feat: add CLI entry point

src/main/kotlin/kestrel/cli/Main.kt

@@ -0,0 +1,28 @@
+package kestrel.cli
+
+import java.io.File
+import kestrel.persistence.Persistence
+
+fun main(arguments: Array<String>) {
+    var dataDir: File? = null
+    var scriptPath: String? = null
+    var index = 0
+    while (index < arguments.size) {
+        val argument = arguments[index]
+        when {
+            argument == "--data" -> {
+                dataDir = File(arguments[index + 1]); index += 2
+            }
+            argument.startsWith("--data=") -> {
+                dataDir = File(argument.substringAfter('=')); index += 1
+            }
+            else -> {
+                scriptPath = argument; index += 1
+            }
+        }
+    }
+    val persistence = dataDir?.let { Persistence(it) }
+    val repl = Repl(persistence = persistence)
+    val reader = if (scriptPath != null) File(scriptPath).bufferedReader() else System.`in`.bufferedReader()
+    reader.use { repl.run(it) }
+}