FreeRTOS version for nRF52840 is oudate

**Is your feature request related to a problem? Please describe.**
FreeRTOS version for nRF52840 is oudate. I am working with a nRF52840 with FreeRTOS distribution made by Adafruit: [https://github.com/adafruit/Adafruit_nR ... 5/freertos](https://github.com/adafruit/Adafruit_nRF52_Arduino/tree/master/cores/nRF5/freertos)

**Describe the solution you'd like**
The problem is that the version in this Github address is outdate, more especifically, it has just one Memory Management Heap Scheme: heap3.c. The version in the FreeRTOS.org has heap1.c, heap2.c, heap3.c, heap4.c and heap5.c. I need to work with heap4.c because it support dinamic memory allocation.

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

**Additional context**

Start by comparing the bundled FreeRTOS files in cores/nRF5/freertos with the FreeRTOS.org distribution referenced in the issue, focusing on the available heap management schemes. Verify the selected heap4 implementation works for the nRF52840 Arduino build; the issue is done when dynamic allocation through heap4 is available without breaking the existing build.

Written by the indexing model from the issue text.