feat(pycardium): Enable framebuf module

The framebuf module provides a framebuffer implementation running purely
in MicroPython which will increase drawing performance by a lot.  A
follow-up change will be necessary to connect this framebuffer
implementation to the display API.

This commit is implements a part of MR !211.

Documentation/pycardium/stdlib.rst

@@ -3,6 +3,14 @@ MicroPython Standard Library
 Pycardium contains some modules from the MicroPython standard library.  These
 are:
 
+.. py:module:: framebuf
+
+``framebuf``
+------------
+Refer to the official `MicroPython docs for framebuf`_.
+
+.. _MicroPython docs for framebuf: https://docs.micropython.org/en/latest/library/framebuf.html
+
 .. py:module:: ubinascii
 
 ``ubinascii``

pycardium/mpconfigport.h

@@ -45,6 +45,7 @@ int mp_hal_trng_read_int(void);
 #define MICROPY_PY_UTIME_MP_HAL             (1)
 #define MICROPY_PY_IO_FILEIO                (1)
 #define MICROPY_PY_UERRNO                   (1)
+#define MICROPY_PY_FRAMEBUF                 (1)
 
 /* Modules */
 #define MODULE_BHI160_ENABLED               (1)