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>

apps/event/main.c

@@ -141,7 +141,7 @@ static void Init_Service_Handlers(void)
     apdu_set_reject_handler(MyRejectHandler);
 }
 
-static void print_usage(char *filename)
+static void print_usage(const char *filename)
 {
     printf("Usage: %s device-id process-id initiating-device-id\n"
            "    event-object-type event-object-instance\n"
@@ -154,7 +154,7 @@ static void print_usage(char *filename)
     printf("       [--version][--help]\n");
 }
 
-static void print_help(char *filename)
+static void print_help(const char *filename)
 {
     printf("Send BACnet ConfirmedEventNotification message to a device.\n");
     printf("device-id:\n"
@@ -246,7 +246,7 @@ int main(int argc, char *argv[])
     bool specific_address = false;
     int argi = 0;
     unsigned int target_args = 0;
-    char *filename = NULL;
+    const char *filename = NULL;
     unsigned found_index = 0;
 
     filename = filename_remove_path(argv[0]);