External dependencies have to be recloned whenever you delete the build folder

[ryanwinter]

This issue is for a: (mark with an x)

- [ ] bug report -> please search issues before submitting
- [x] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)

Minimal steps to reproduce

Follow guide steps here: https://github.com/Azure-Samples/iot-middleware-freertos-samples/tree/main/demos/projects/NXP/mimxrt1060#build-the-image

During the configure step, multiple repositories are cloned into the temporary build directory. There are two disadvantages here:

1. The repositories need to be recloned every time the build directory is deleted.
2. Can confuse debugger if files are temporary.

Expected/desired behavior

External repositories to not be stored in temporary build directories, and to be easy to update when needed.

[ryanwinter]

eclipse-threadx/getting-started#74

[hihigupt]

Our cmake make sure if you have pre-seeded external dependencies, we will not download it to temporary build folder. To make cmake aware about these dependencies, user should set cmake variables with their path e.g.: FREERTOS_PATH for freertos.

Check this cmake for the logic.

iot-middleware-freertos-samples/cmake/common/utilities.cmake

Line 28 in 130bc92

if(FREERTOS_PATH)