bricks/_common/mpconfigport: enable unicode support

Enable MICROPY_PY_BUILTINS_STR_UNICODE on hubs with PYBRICKS_OPT_EXTRA_MOD.

Without this, there is not any difference between str and bytes, which
can make it hard to work with multi-byte characters.

Author: dlech

CHANGELOG.md

@@ -5,7 +5,7 @@
 ## [Unreleased]
 
 ### Changed
-
+- Enabled UTF-8 support for `str` objects.
 - The method `DriveBase.angle()` now returns a float ([support#1844]). This
   makes it properly equivalent to `hub.imu.heading`.
 

bricks/_common/mpconfigport.h

@@ -80,6 +80,7 @@
 #define MICROPY_PY_BUILTINS_SLICE               (PYBRICKS_OPT_EXTRA_MOD)
 #define MICROPY_PY_BUILTINS_PROPERTY            (0)
 #define MICROPY_PY_BUILTINS_MIN_MAX             (1)
+#define MICROPY_PY_BUILTINS_STR_UNICODE         (PYBRICKS_OPT_EXTRA_MOD)
 #define MICROPY_PY___FILE__                     (0)
 #define MICROPY_PY_MICROPYTHON_MEM_INFO         (1)
 #define MICROPY_PY_GC                           (PYBRICKS_OPT_EXTRA_MOD)