Add support for LS20031 GPS module. (#5718)

Hardware documentation referenced:
- https://cdn.sparkfun.com/datasheets/GPS/LS20030~3_datasheet_v1.3.pdf
- https://cdn-shop.adafruit.com/datasheets/PMTK%20command%20packet-Complete-C39-A01.pdf

src/gps/GPS.h

@@ -29,7 +29,8 @@ typedef enum {
     GNSS_MODEL_MTK_L76B,
     GNSS_MODEL_MTK_PA1616S,
     GNSS_MODEL_AG3335,
-    GNSS_MODEL_AG3352
+    GNSS_MODEL_AG3352,
+    GNSS_MODEL_LS20031
 } GnssModel_t;
 
 typedef enum {
@@ -239,4 +240,4 @@ class GPS : private concurrency::OSThread
 };
 
 extern GPS *gps;
-#endif // Exclude GPS
+#endif // Exclude GPS