examples: Implement directories.zig, an example that uses directory operations

examples/directories.zig

@@ -0,0 +1,38 @@
+const std = @import("std");
+const Io = std.Io;
+
+const Simulator = @import("zigmulator");
+
+fn directoriesProgram(init: std.process.Init) anyerror!void {
+    try Io.Dir.cwd().createDir(init.io, "logs", .default_dir);
+
+    const logs_dir = try Io.Dir.cwd().openDir(init.io, "logs", .{});
+    defer logs_dir.close(init.io);
+
+    const created_file = try logs_dir.createFile(init.io, "message.txt", .{});
+    var writer = created_file.writerStreaming(init.io, &.{});
+    try writer.interface.writeAll("created inside an opened directory");
+    try writer.interface.flush();
+    created_file.close(init.io);
+
+    const opened_file = try logs_dir.openFile(init.io, "message.txt", .{});
+    defer opened_file.close(init.io);
+
+    var buffer: [128]u8 = undefined;
+    const read_len = try opened_file.readPositionalAll(init.io, &buffer, 0);
+
+    var stdout = Io.File.stdout().writerStreaming(init.io, &.{});
+    try stdout.interface.print("logs/message.txt: {s}\n", .{buffer[0..read_len]});
+    try stdout.interface.flush();
+}
+
+pub fn main(init: std.process.Init) !void {
+    var sim: Simulator = undefined;
+    sim.init(std.heap.page_allocator, init.io);
+    defer sim.deinit();
+
+    try sim.addExecutable("directories", directoriesProgram);
+    try sim.spawn("directories", .{});
+
+    while (sim.scheduleOne()) {}
+}