scripts: runners: check for required programs

Add self.require() checks before running commands. Increase test
coverage, including for this feature, while we are here.

Signed-off-by: Marti Bolivar <marti.bolivar@nordicsemi.no>

scripts/west_commands/runners/esp32.py

@@ -78,6 +78,7 @@ class Esp32BinaryRunner(ZephyrBinaryRunner):
             partition_table_bin=args.esp_flash_partition_table)
 
     def do_run(self, command, **kwargs):
+        self.require(self.espidf)
         bin_name = path.splitext(self.elf)[0] + path.extsep + 'bin'
         cmd_convert = [self.espidf, '--chip', 'esp32', 'elf2image', self.elf]
         cmd_flash = [self.espidf, '--chip', 'esp32', '--port', self.device,