cli: add basic probe-rs support

OpenOCD can be somewhat outdated. `probe-rs` is a more modern tool
written in Rust with many interesting features, like built-in RTT
logging support.

This commit just adds basic support, to be able to flash devices with
probe-rs and debug them.

compileopts/config.go

@@ -539,7 +539,7 @@ func (c *Config) Programmer() (method, openocdInterface string) {
 	case "openocd", "msd", "command", "adb":
 		// The -programmer flag only specifies the flash method.
 		return c.Options.Programmer, c.Target.OpenOCDInterface
-	case "bmp":
+	case "bmp", "probe-rs":
 		// The -programmer flag only specifies the flash method.
 		return c.Options.Programmer, ""
 	default: