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/object/bitstring_value.c

@@ -172,7 +172,7 @@ bool BitString_Value_Present_Value(
  * @return  true if value is within range and copied
  */
 bool BitString_Value_Present_Value_Set(
-    uint32_t object_instance, BACNET_BIT_STRING *value)
+    uint32_t object_instance, const BACNET_BIT_STRING *value)
 {
     bool status = false;
     struct object_data *pObject;
@@ -306,7 +306,7 @@ BACNET_RELIABILITY BitString_Value_Reliablity(
  * @param  object_instance - object-instance number of the object
  * @return  true the status flag is in Fault
  */
-static bool BitString_Value_Object_Fault(struct object_data *pObject)
+static bool BitString_Value_Object_Fault(const struct object_data *pObject)
 {
     bool fault = false;
 
@@ -460,7 +460,7 @@ bool BitString_Value_Object_Name(
  *
  * @return  true if object-name was set
  */
-bool BitString_Value_Name_Set(uint32_t object_instance, char *new_name)
+bool BitString_Value_Name_Set(uint32_t object_instance, const char *new_name)
 {
     bool status = false; /* return value */
     struct object_data *pObject;
@@ -498,15 +498,15 @@ const char *BitString_Value_Name_ASCII(uint32_t object_instance)
  * @return  C-string pointer to the description,
  *  or NULL if object doesn't exist
  */
-char *BitString_Value_Description(uint32_t object_instance)
+const char *BitString_Value_Description(uint32_t object_instance)
 {
-    char *name = NULL; /* return value */
-    struct object_data *pObject;
+    const char *name = NULL; /* return value */
+    const struct object_data *pObject;
 
     pObject = BitString_Value_Object(object_instance);
     if (pObject) {
         if (pObject->Description) {
-            name = (char *)pObject->Description;
+            name = pObject->Description;
         } else {
             name = "";
         }
@@ -525,7 +525,7 @@ char *BitString_Value_Description(uint32_t object_instance)
  * @return True on success, false otherwise.
  */
 bool BitString_Value_Description_Set(
-    uint32_t object_instance, char *value)
+    uint32_t object_instance, const char *value)
 {
     bool status = false; /* return value */
     struct object_data *pObject;