examples/hello_rust: Add feature to blink the LED

[rushabhvg]

Summary

• The existing Rust Demo App hello_rust only prints a message, it might be simplistic for a NuttX App. This PR extends hello_rust to call NuttX POSIX APIs like open() and ioctl(), so that it blinks an LED.
• If the LED Driver is not available, the app terminates gracefully.
• The updated hello_rust app is also used for testing the GPIO and LED Drivers for Ox64 BL808 SBC in Google Summer of Code.
• The code is based on examples/leds in C.

Modified file examples/hello_rust:

• hello_rust_main.rs: Call LED and GPIO drivers to turn the LED on and off

Impact

• With this PR, NuttX for Ox64 will be able to test and verify the operation of LED through GPIO pins.
• No impact on existing code, since we are extending the functionality of a Rust Demo App.
• Build Instructions for QEMU RISC-V 32-bit
• Build Instructions for QEMU RISC-V 64-bit
• Build Instructions for Ox64

Testing

We tested the updated hello_rust app on Ox64 Emulator. The app blinks the Simulated LED correctly:

• Build Instructions for Ox64
• Ox64 Demo Video
• Ox64 Test Log
• Test Log for Ox64 Emulator

rushabhvg@rushabhvg-laptop:~/Desktop/nuttx$ ./temu nuttx.cfg
TinyEMU Emulator for Ox64 BL808 RISC-V SBC

NuttShell (NSH)
nsh> nx_start: CPU0: Beginning Idle Loop

nsh> uname -a
nxposix_spawn_exec: ERROR: exec failed: 2
NuttX 0.0.0 b8c1ce45e6 Jul  8 2024 13:30:17 risc-v ox64

nsh> hello_rust
nxtask_activate: hello_rust pid=4,TCB=0x5040b290
nxsig_tcbdispatch: TCB=0x5040b290 pid=4 signo=0 code=0 value=0 masked=NO
Hello, Rust!!
Opening /dev/userleds
Set LED 1 to 1
{"nuttxemu":{"gpio29":1}}
Sleeping...
Set LED 1 to 0
{"nuttxemu":{"gpio29":0}}
nxsig_tcbdispatch: TCB=0x5040af80 pid=3 signo=17 code=5 value=0 masked=NO
nxtask_exit: hello_rust pid=4,TCB=0x5040b290
nxsig_tcbdispatch: TCB=0x5040af80 pid=3 signo=17 code=5 value=0 masked=NO

[lupyuen]

Please retest Rust Blinky on Ox64 Emulator thanks :-)