Use usleep instead of sleep/nanosleep on Mbed OS.

[pan-]

Problem

nanosleep is not available on Mbed OS and sleep as a different semantic compared to POSIX (not tie to newlib).
Some unit tests actively use this feature which cause a compilation error.

Change overview

In unit tests, use usleep instead of nanosleep or sleep when compiled for Mbed OS.

Testing

How was this tested? (at least one bullet point required)

Existing unit tests.

[github-actions]

Size increase report for "esp32-example-build" from 15669b6

File	Section	File	VM
chip-temperature-measurement-app.elf	.flash.text	60	60
chip-all-clusters-app.elf	.flash.text	16	16

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-temperature-measurement-app.elf and ./pull_artifact/chip-temperature-measurement-app.elf:

sections,vmsize,filesize
.flash.text,60,60
[Unmapped],0,-60

Comparing ./master_artifact/chip-persistent-storage.elf and ./pull_artifact/chip-persistent-storage.elf:

sections,vmsize,filesize

Comparing ./master_artifact/chip-pigweed-app.elf and ./pull_artifact/chip-pigweed-app.elf:

sections,vmsize,filesize

Comparing ./master_artifact/chip-lock-app.elf and ./pull_artifact/chip-lock-app.elf:

sections,vmsize,filesize

Comparing ./master_artifact/chip-all-clusters-app.elf and ./pull_artifact/chip-all-clusters-app.elf:

sections,vmsize,filesize
.xt.lit._ZN4chip6System5Mutex6UnlockEv,0,128
.xt.lit._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE10_PostEventEPKNS0_15ChipDeviceEventE,0,80
.xt.prop._ZN4chip11DeviceLayer8Internal26GenericPlatformManagerImplINS0_19PlatformManagerImplEE14_InitChipStackEv,0,40
.flash.text,16,16
.xt.prop._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE14_LockChipStackEv,0,-12
.xt.prop._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE15_StartChipTimerEj,0,-12
.xt.prop._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE16_UnlockChipStackEv,0,-12
[Unmapped],0,-16
.xt.lit._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE14_LockChipStackEv,0,-48
.xt.lit._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE15_StartChipTimerEj,0,-48
.xt.lit._ZN4chip11DeviceLayer8Internal35GenericPlatformManagerImpl_FreeRTOSINS0_19PlatformManagerImplEE16_UnlockChipStackEv,0,-48
.xt.prop._ZN4chip6System5Mutex6UnlockEv,0,-108

Comparing ./master_artifact/chip-shell.elf and ./pull_artifact/chip-shell.elf:

sections,vmsize,filesize

[pan-]

I use usleep everywhere, everything seems fine.

[bzbarsky-apple]

@pan- See review comments?

[ATmobica]

@bzbarsky-apple Hi, @pan- is on holiday so I take over this PR. I changed the casting according to your comments