Refactor builtin commands dispatcher

src/builtin/cmds/cd.zig

@@ -1,20 +1,18 @@
 const std = @import("std");
 
-pub fn execute(
-    io: std.Io,
-    environ: *const std.process.Environ.Map,
-    argv: []const []const u8,
-) !void {
-    const path = if (argv.len >= 2)
-        argv[1]
+const types = @import("../types.zig");
+
+pub fn execute(ctx: types.BuiltinCommandContext) !void {
+    const path = if (ctx.argv.len >= 2)
+        ctx.argv[1]
     else
-        environ.get("USERPROFILE") orelse environ.get("HOME") orelse {
+        ctx.shell.environ.get("USERPROFILE") orelse ctx.shell.environ.get("HOME") orelse {
             std.debug.print("xsh: cd: cannot find home directory\n", .{});
             return;
         };
 
-    var dir = try std.Io.Dir.cwd().openDir(io, path, .{});
-    defer dir.close(io);
+    var dir = try std.Io.Dir.cwd().openDir(ctx.io, path, .{});
+    defer dir.close(ctx.io);
 
-    try std.process.setCurrentDir(io, dir);
+    try std.process.setCurrentDir(ctx.io, dir);
 }