esp32: Add core dump saving to flash feature

Complimentary changes:
1) Partition table definitions files with core dump partition
2) Special sub-type for core dump partition
3) Special version of spi_flash_xxx
4) espcoredump.py is script to get core dump from flash and print useful info
5) FreeRTOS API was extended to get tasks snapshots

components/freertos/include/freertos/task.h

@@ -181,6 +181,18 @@ typedef struct xTASK_STATUS
 	uint16_t usStackHighWaterMark;	/* The minimum amount of stack space that has remained for the task since the task was created.  The closer this value is to zero the closer the task has come to overflowing its stack. */
 } TaskStatus_t;
 
+/*
+ * Used with the uxTaskGetSnapshotAll() function to save memory snapshot of each task in the system.
+ * We need this struct because TCB_t is defined (hidden) in tasks.c.
+ */
+typedef struct xTASK_SNAPSHOT
+{
+    void        *pxTCB;         /* Address of task control block. */
+    StackType_t *pxTopOfStack;  /* Points to the location of the last item placed on the tasks stack. */
+    StackType_t *pxEndOfStack;  /* Points to the end of the stack. pxTopOfStack < pxEndOfStack, stack grows hi2lo
+                                    pxTopOfStack > pxEndOfStack, stack grows lo2hi*/
+} TaskSnapshot_t;
+
 /* Possible return values for eTaskConfirmSleepModeStatus(). */
 typedef enum
 {
@@ -2173,6 +2185,9 @@ eSleepModeStatus eTaskConfirmSleepModeStatus( void ) PRIVILEGED_FUNCTION;
  */
 void *pvTaskIncrementMutexHeldCount( void );
 
+/* Used by core dump facility to get list of task handles. */
+UBaseType_t uxTaskGetSnapshotAll( TaskSnapshot_t * const pxTaskSnapshotArray, const UBaseType_t uxArraySize, UBaseType_t * const pxTcbSz );
+
 #ifdef __cplusplus
 }
 #endif