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/rx62n/device.c

@@ -107,11 +107,12 @@ static struct my_object_functions *Device_Objects_Find_Functions(
 }
 
 static int Read_Property_Common(
-    struct my_object_functions *pObject, BACNET_READ_PROPERTY_DATA *rpdata)
+    const struct my_object_functions *pObject,
+    BACNET_READ_PROPERTY_DATA *rpdata)
 {
     int apdu_len = BACNET_STATUS_ERROR;
     BACNET_CHARACTER_STRING char_string;
-    char *pString = "";
+    const char *pString = "";
     uint8_t *apdu = NULL;
 #if (BACNET_PROTOCOL_REVISION >= 14)
     struct special_property_list_t property_list;

ports/rx62n/ethernet.c

@@ -174,7 +174,7 @@ uint16_t ethernet_receive(BACNET_ADDRESS *src, /* source address */
     return pdu_len;
 }
 
-void ethernet_set_my_address(BACNET_ADDRESS *my_address)
+void ethernet_set_my_address(const BACNET_ADDRESS *my_address)
 {
     int i = 0;