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>

ports/atmega168/ai.h

@@ -37,13 +37,13 @@ extern "C" {
         uint32_t object_instance);
     bool Analog_Input_Name_Set(
         uint32_t object_instance,
-        char *new_name);
+        const char *new_name);
 
-    char *Analog_Input_Description(
+    const char *Analog_Input_Description(
         uint32_t instance);
     bool Analog_Input_Description_Set(
         uint32_t instance,
-        char *new_name);
+        const char *new_name);
 
     bool Analog_Input_Units_Set(
         uint32_t instance,

ports/atmega168/dlmstp.c

@@ -226,7 +226,7 @@ static void MSTP_Send_Frame(
     uint8_t frame_type, /* type of frame to send - see defines */
     uint8_t destination, /* destination address */
     uint8_t source, /* source address */
-    uint8_t *pdu, /* any data to be sent - may be null */
+    const uint8_t *pdu, /* any data to be sent - may be null */
     uint16_t pdu_len)
 { /* number of bytes of data (up to 501) */
     uint8_t crc8 = 0xFF; /* used to calculate the crc value */
@@ -635,7 +635,7 @@ static bool MSTP_Master_Node_FSM(void)
             if (TransmitPacketLen) {
                 MSTP_Send_Frame(FRAME_TYPE_BACNET_DATA_NOT_EXPECTING_REPLY,
                     MSTP_BROADCAST_ADDRESS, This_Station,
-                    (uint8_t *)&TransmitPacket[0], TransmitPacketLen);
+                    &TransmitPacket[0], TransmitPacketLen);
                 FrameCount++;
             } else {
                 /* NothingToSend */
@@ -959,7 +959,7 @@ static bool MSTP_Master_Node_FSM(void)
                 /* Note: optimized such that we are never a client */
                 MSTP_Send_Frame(FRAME_TYPE_BACNET_DATA_NOT_EXPECTING_REPLY,
                     TransmitPacketDest, This_Station,
-                    (uint8_t *)&TransmitPacket[0], TransmitPacketLen);
+                    &TransmitPacket[0], TransmitPacketLen);
                 MSTP_Flag.TransmitPacketPending = false;
                 Master_State = MSTP_MASTER_STATE_IDLE;
             } else {

ports/atmega168/rs485.c

@@ -144,7 +144,7 @@ void RS485_Turnaround_Delay(void)
  * @param buffer - data to send
  * @param nbytes - number of bytes of data
  */
-void RS485_Send_Data(uint8_t *buffer,
+void RS485_Send_Data(const uint8_t *buffer,
     uint16_t nbytes)
 {
     while (nbytes) {

ports/atmega168/rs485.h

@@ -21,7 +21,7 @@ extern "C" {
         bool enable);
 
     void RS485_Send_Data(
-        uint8_t * buffer,       /* data to send */
+        const uint8_t * buffer, /* data to send */
         uint16_t nbytes);       /* number of bytes of data */
 
     bool RS485_ReceiveError(