Restructure NRF Logging for SDK 14.2 such that logging entries printf stdout (when enabled with softdevice.nrf_enable_logging config entry)

Author: pi-anl

targets/TARGET_NORDIC/TARGET_NRF5x/TARGET_SDK_14_2/TARGET_SOFTDEVICE_S132_FULL/mbed_lib.json

@@ -1,5 +1,12 @@
 {
     "name": "softdevice",
+    "config": {
+        "nrf_enable_logging": {
+            "help": "When '1' NRF_LOG_* outputs will be sent to stdout.",
+            "value": "0",
+            "macro_name": "NRF_LOG_ENABLED"
+        }
+    },
     "macros": [
         "SOFTDEVICE_PRESENT=1",
         "S132",
@@ -34,7 +41,8 @@
         "NRF_SDH_BLE_STACK_OBSERVER_PRIO=0",
         "NRF_SDH_SOC_STACK_OBSERVER_PRIO=0",
         "FDS_BACKEND=2",
-        "SWI_DISABLE1=1"
+        "SWI_DISABLE1=1",
+        "NRF_STRERROR_ENABLED=1"
     ],
     "target_overrides": {
         "*": {

targets/TARGET_NORDIC/TARGET_NRF5x/TARGET_SDK_14_2/TARGET_SOFTDEVICE_S140_FULL/mbed_lib.json

@@ -1,5 +1,12 @@
 {
     "name": "softdevice",
+    "config": {
+        "nrf_enable_logging": {
+            "help": "When '1' NRF_LOG_* outputs will be sent to stdout.",
+            "value": "0",
+            "macro_name": "NRF_LOG_ENABLED"
+        }
+    },
     "macros": [
         "SOFTDEVICE_PRESENT=1",
         "S140",
@@ -34,7 +41,8 @@
         "NRF_SDH_BLE_STACK_OBSERVER_PRIO=0",
         "NRF_SDH_SOC_STACK_OBSERVER_PRIO=0",
         "FDS_BACKEND=2",
-        "SWI_DISABLE1=1"
+        "SWI_DISABLE1=1",
+        "NRF_STRERROR_ENABLED=1"
     ],
     "target_overrides": {
         "*": {

targets/TARGET_NORDIC/TARGET_NRF5x/TARGET_SDK_14_2/libraries/README.md

@@ -6,6 +6,10 @@ components/libraries
 
 Only essential folders have been copied over.
 
+`experimental_log/nrf_log.h` has been removed and reimplemented in `TARGET_NRF5x/nrf_log.h` to 
+provide optional logging via mbed stdout. Only the minimum required headers have been left in 
+experimental_log folder.
+
 Removed:
  * block_dev/
  * bootloader/