Fix cardputer boot loop, and do some cleanup.

- For `cardputer_keyboard.c`, allocate `DemuxKeyMatrix` it creates and the objects it holds (all the way down) on the port heap, because it lives past VM's.
- To do the above, add support for non-VM heap for `DemuxKeyMatrix` and the `keypad` allocations it needs by passing an arg `use_gc_allocator`, as is done in `lvfontio`.
- Add `mp_obj_port_malloc()`, `mp_obj_port_malloc_var()`, `mp_obj_new_port_tuple()`, all of which allocate on the port heap, not the VM heap.
- Add `port_malloc_zero()`, because `port_malloc()` did not zero out its allocation, unlike VM heap allocations. I got caught by this.
- Move `port_gc_collect()` from `main.c` to `supervisor/port.c` for consistency. This function is not actually used by anyone, but I was considering using it.
- Add an `MP_WEAK` `mp_board_init()`, for board-specific initializations needed when a VM starts. Also considered, but not used. Added anyway for possible future use.
- Add an `MP_WEAK` `board_gc_collect()`, for board-specific gc. Not used.
- Add an `MP_WEAK` `port_gc_collect()`, for port-specific gc. Not used.
- Don't duplicate keyboard code between `boards/m5stack_cardputer` and `boards/m5stack_cardputer_ros`. Instead, add a `ports/espressif/module` directory for this code, in the style of a port-specific `module` directory, like the port-specific `bindings` directories.

Author: dhalbert

main.c

@@ -207,6 +207,9 @@ static void start_mp(safe_mode_t safe_mode) {
 
     // Always return to root
     common_hal_os_chdir("/");
+
+    // Initialization for individual boards when a VM starts.
+    mp_board_init();
 }
 
 static void stop_mp(void) {
@@ -1149,6 +1152,7 @@ void gc_collect(void) {
     gc_collect_root((void **)&MP_STATE_VM(vfs_mount_table), sizeof(mp_vfs_mount_t) / sizeof(mp_uint_t));
 
     port_gc_collect();
+    board_gc_collect();
 
     background_callback_gc_collect();
 
@@ -1179,10 +1183,6 @@ void gc_collect(void) {
     gc_collect_end();
 }
 
-// Ports may provide an implementation of this function if it is needed
-MP_WEAK void port_gc_collect(void) {
-}
-
 size_t gc_get_max_new_split(void) {
     return port_heap_get_largest_free_size();
 }

ports/espressif/boards/m5stack_cardputer/mpconfigboard.mk

@@ -13,4 +13,4 @@ CIRCUITPY_ESP_FLASH_SIZE = 8MB
 CIRCUITPY_ESPCAMERA = 0
 CIRCUITPY_MAX3421E = 0
 
-SRC_C += boards/$(BOARD)/cardputer_keyboard.c
+SRC_C += module/cardputer_keyboard.c