refactor: zigify imports and usages

src/testing.zig

@@ -181,8 +181,8 @@ pub fn expectEqualCells(origin: Point, size: Point, expected: []const Cell, actu
     // test failed
     try buffer.flush();
 
-    std.debug.lockStdErr();
-    defer std.debug.unlockStdErr();
+    debug.lockStdErr();
+    defer debug.unlockStdErr();
 
     const std_writer = std.io.getStdErr().writer();
     try std_writer.writeAll(output.items);
@@ -190,6 +190,7 @@ pub fn expectEqualCells(origin: Point, size: Point, expected: []const Cell, actu
 }
 
 const std = @import("std");
+const debug = std.debug;
 const testing = std.testing;
 const Allocator = std.mem.Allocator;
 const event = @import("event.zig");