Make most of functions const correct (#714)

* Make most of the functions const correct

Used clang-tidy and sonarlint to help find places where const could
pretty easily applied. Also lot of hand work.

This commit does not yet touch handlers and typedefs of those.

* Fix Arduino uno handler_who_is() has extra parenthesis

For some reason there is extra parenthesis. Remove it this is more
likely buildable.

* Bugfix/bacapp: Fix uninitilized array_index

We have changed bacapp_snprintf_value() to be const correct. After that
we got

```
/home/runner/work/bacnet-stack/bacnet-stack/src/bacnet/bacapp.c:3183:27: warning: 4th function call argument is an uninitialized value [core.CallAndMessage]
                ret_val = bacapp_snprintf_weeklyschedule(
                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
```

So analyzer could now spot that we do not actually initilize array_index
at all. Fix this by setting array_index to zero. Note that I actually do
not know if zeroing is right thing to do here. I choose zero as if this
has worked before it is most likely that it will work with zero value.

* cmake: Add and ignore Wwrite-strings compiler option

Wwrite-strings helps find places where const correctness is broken.

Example it will warn about these

```C

void func1(char* str);

func("test") /* "test" is const so we should not pass it to func1().

char* func2()
{
  return "test"; /* func2() should return const char*.
}
```

We still need to ignore it as not all are fixed but let's add it already
so we remember that it should be opened at some point.

---------

Co-authored-by: Kari Argillander <kari.argillander@fidelix.com>

src/bacnet/basic/npdu/s_router.c

@@ -46,12 +46,12 @@
  */
 int Send_Network_Layer_Message(BACNET_NETWORK_MESSAGE_TYPE network_message_type,
     BACNET_ADDRESS *dst,
-    int *iArgs)
+    const int *iArgs)
 {
     int len = 0;
     int pdu_len = 0;
     int bytes_sent = 0;
-    int *pVal = iArgs; /* Start with first value */
+    const int *pVal = iArgs; /* Start with first value */
     bool data_expecting_reply = false;
     BACNET_NPDU_DATA npdu_data;
     BACNET_ADDRESS bcastDest;
@@ -209,7 +209,7 @@ void Send_I_Am_Router_To_Network(const int DNET_list[])
 {
     /* Use a NULL dst here since we want a broadcast MAC address. */
     Send_Network_Layer_Message(
-        NETWORK_MESSAGE_I_AM_ROUTER_TO_NETWORK, NULL, (int *)DNET_list);
+        NETWORK_MESSAGE_I_AM_ROUTER_TO_NETWORK, NULL, DNET_list);
 }
 
 /** Finds a specific router, or all reachable BACnet networks.
@@ -253,7 +253,7 @@ void Send_Initialize_Routing_Table(BACNET_ADDRESS *dst, const int DNET_list[])
 {
     /* Use a NULL dst here since we want a broadcast MAC address. */
     Send_Network_Layer_Message(
-        NETWORK_MESSAGE_INIT_RT_TABLE, dst, (int *)DNET_list);
+        NETWORK_MESSAGE_INIT_RT_TABLE, dst, DNET_list);
 }
 
 /** Sends our Routing Table, built from our DNET[] array, as an ACK.
@@ -277,7 +277,7 @@ void Send_Initialize_Routing_Table_Ack(
     BACNET_ADDRESS *dst, const int DNET_list[])
 {
     Send_Network_Layer_Message(
-        NETWORK_MESSAGE_INIT_RT_TABLE_ACK, dst, (int *)DNET_list);
+        NETWORK_MESSAGE_INIT_RT_TABLE_ACK, dst, DNET_list);
 }
 
 /**

src/bacnet/basic/npdu/s_router.h

@@ -25,7 +25,7 @@ extern "C" {
     int Send_Network_Layer_Message(
         BACNET_NETWORK_MESSAGE_TYPE network_message_type,
         BACNET_ADDRESS * dst,
-        int *iArgs);
+        const int *iArgs);
     BACNET_STACK_EXPORT
     void Send_Who_Is_Router_To_Network(
         BACNET_ADDRESS * dst,