feat(debug): conditionally enable debug button on Nano ESP32

If the `debug.executable` variable is null or unset, the Debug button
appears grayed out. The new IDE also takes current parameters into
account, allowing to conditionally enable the Debug button only when
some conditions are met.

Author: pillo79

Diff for: boards.txt

@@ -29910,6 +29910,7 @@ nano_nora.tools.esptool_py.program.pattern_args=--chip {build.mcu} --port "{seri
 nano_nora.tools.esptool_py.erase.pattern_args=--chip {build.mcu} --port "{serial.port}" --before default_reset --after hard_reset erase_flash
 
 nano_nora.programmer.default=esptool
+nano_nora.debug.executable=
 
 nano_nora.menu.PartitionScheme.default=With FAT partition (default)
 nano_nora.menu.PartitionScheme.spiffs=With SPIFFS partition (advanced)
@@ -29922,6 +29923,7 @@ nano_nora.menu.PinNumbers.byGPIONumber.build.disable_pin_remap=-DBOARD_USES_HW_G
 nano_nora.menu.USBMode.default=Normal mode (TinyUSB)
 nano_nora.menu.USBMode.hwcdc=Debug mode (Hardware CDC)
 nano_nora.menu.USBMode.hwcdc.build.usb_mode=1
+nano_nora.menu.USBMode.hwcdc.debug.executable={build.path}/{build.project_name}.elf
 
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