To allow overriding of the boot stack size from the Mbed configuration
system, consistently use MBED_CONF_TARGET_BOOT_STACK_SIZE rather than
MBED_BOOT_STACK_SIZE.

Fixes #10319

* Update all scatterfiles to define MBED_RAM_START and MBED_RAM_SIZE.  These
get defined in mbed_lib.json when building with a SoftDevice but were missing
when no SoftDevice is brought in.
* Remove SDK 14.2 SoftDevice files.
* Add missing header file to qspi_api.c.

- Adjust memory for SoftDevice
    - Enable PRIO=5 for interrupt priority check
    - Change NRF_SD_BLE_API_VERSION to 6
    - Add handle and buffer for advertising and scanning
    - Remove guard for phy update
    - Change scatter files and mbed_lib.json for PR #8607

Add missing noinit section.

GCC and IAR ISR stack sizes have been set to 0x800.
(ARM compiler does not set stack size explicitly).

* Add NRF_SD_BLE_API_VERSION=5 macro to MCU_NRF52832 target
* Added initial Softdevice v5 API support for nRF5XPalGattClient.cpp
* Added initial Softdevice v5 API support for nRF5xGap.h
* Added initial Softdevice v5 API support for nRF5xGattServer.cpp
* Make sure the ah() hash function used by the security manager is declared with C linkage
* Removed 'ARM porting pending' checks in Nordic SDK
* Added BLE configuration to mbed_lib.json for NRF52x targets
* Migrated APIs and events model for Nordic SDK14.2 & SD API v5 in btle.cpp; adopted polling dispatch model
* Migrated APIs and events model for Nordic SDK14.2 & SD API v5 in nRF5xn.cpp
* Migrated APIs and events model for Nordic SDK14.2 & SD API v5 in nRF5xGap.cpp
* Added const qualifier to hwCallbacks's p_ble_evt parameter in nRF5xGattServer
* Add workaround to enable Radio Notification module from Nordic SDK
  * Disabled SWI1 interrupt manually from SWI driver module
    * Added missing include directive for "nrf_nvic.h" in ble_radio_notification.c
* Set correct number of custom UUIDs
* Adjust Softdevice RAM requirements for NRF52832/S132
  * RAM settings for the application were adjusted as follow:
    * Start: 0x20003800
    * Size: 0xC800
* Adjust Softdevice RAM requirements for NRF52840/S140
  * RAM settings for the application were adjusted as follow:
    * Start: 0x20003700 (was 0x20003000)
    * Size: 0xC900
* Added 3dBm as a permitted TX Power value for NRF52832
* Fix address type recovery in GAP
* Return min non-connectable adv interval compatible with infrastrcture's expectations
* Moved BLE driver from TARGET_SDK_14_2/FEATURE_BLE to TARGET_SDK_14_2/TARGET_SOFTDEVICE_COMMON/ble

Various bug fixes:

 * Moved SPIM3 location in vector table based on new location in SDK 14.2.
 * Updated vector table entries and size in startup code and linker scripts.
 * Added missing vector table RAM section to IAR linker script.

Ability to swap SoftDevices using the mbed configuration system.

For example, build NRF52840_DK without SoftDevice:

    "target_overrides": {
        "*": {
            "target.MERGE_SOFT_DEVICE": false,
            "target.extra_labels_remove": ["SOFTDEVICE_COMMON", "SOFTDEVICE_S140"],
            "target.extra_labels_add": ["SOFTDEVICE_NONE"]
        }
    }

Pinned down vector table to beginningn of RAM.

Flash and RAM offsets have been modified to fit new SoftDevice