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/epics/main.c

@@ -710,7 +710,7 @@ static void BuildPropRequest(BACNET_READ_ACCESS_DATA *rpm_object)
  *         of the property list.
  */
 static uint8_t Read_Properties(
-    uint32_t device_instance, BACNET_OBJECT_ID *pMyObject)
+    uint32_t device_instance, const BACNET_OBJECT_ID *pMyObject)
 {
     uint8_t invoke_id = 0;
     struct special_property_list_t PropertyListStruct;
@@ -884,7 +884,7 @@ static EPICS_STATES ProcessRPMData(
     return nextState;
 }
 
-static void print_usage(char *filename)
+static void print_usage(const char *filename)
 {
     printf("Usage: %s [-v] [-d] [-p sport] [-t target_mac [-n dnet]]"
            " device-instance\n",
@@ -892,7 +892,7 @@ static void print_usage(char *filename)
     printf("       [--version][--help]\n");
 }
 
-static void print_help(char *filename)
+static void print_help(const char *filename)
 {
     (void)filename;
     printf("Generates Full EPICS file, including Object and Property List\n");
@@ -921,7 +921,7 @@ static int CheckCommandLineArgs(int argc, char *argv[])
     int i;
     bool bFoundTarget = false;
     int argi = 0;
-    char *filename = NULL;
+    const char *filename = NULL;
 
     filename = filename_remove_path(argv[0]);
     for (argi = 1; argi < argc; argi++) {