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

--legacyalign, --no_legacyalign are deprecated from ARMC6 compiler, in order to
remove deprecated flags all linker files (GCC and IAR as well to have uniformity)
should strictly align to 8-byte boundary

IAR linker script was using memory settings from the NRF52840 and
not the NRF52832.

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