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/bacfile.c

@@ -331,7 +331,7 @@ uint32_t bacfile_read(uint32_t object_instance, uint8_t *buffer,
  * @param  buffer_size - in bytes
  * @return  file size in bytes
  */
-uint32_t bacfile_write(uint32_t object_instance, uint8_t *buffer,
+uint32_t bacfile_write(uint32_t object_instance, const uint8_t *buffer,
     uint32_t buffer_size)
 {
     const char *pFilename = NULL;
@@ -877,14 +877,14 @@ bool bacfile_write_stream_data(BACNET_ATOMIC_WRITE_FILE_DATA *data)
     return found;
 }
 
-bool bacfile_write_record_data(BACNET_ATOMIC_WRITE_FILE_DATA *data)
+bool bacfile_write_record_data(const BACNET_ATOMIC_WRITE_FILE_DATA *data)
 {
     const char *pFilename = NULL;
     bool found = false;
     FILE *pFile = NULL;
     uint32_t i = 0;
     char dummy_data[FILE_RECORD_SIZE];
-    char *pData = NULL;
+    const char *pData = NULL;
 
     pFilename = bacfile_pathname(data->object_instance);
     if (pFilename) {
@@ -913,7 +913,7 @@ bool bacfile_write_record_data(BACNET_ATOMIC_WRITE_FILE_DATA *data)
                 }
             }
             for (i = 0; i < data->type.record.returnedRecordCount; i++) {
-                if (fwrite(octetstring_value(&data->fileData[i]),
+                if (fwrite(octetstring_value((BACNET_OCTET_STRING*)&data->fileData[i]),
                         octetstring_length(&data->fileData[i]), 1,
                         pFile) != 1) {
                     /* do something if it fails? */
@@ -927,7 +927,7 @@ bool bacfile_write_record_data(BACNET_ATOMIC_WRITE_FILE_DATA *data)
 }
 
 bool bacfile_read_ack_stream_data(
-    uint32_t instance, BACNET_ATOMIC_READ_FILE_DATA *data)
+    uint32_t instance, const BACNET_ATOMIC_READ_FILE_DATA *data)
 {
     bool found = false;
     FILE *pFile = NULL;
@@ -939,7 +939,7 @@ bool bacfile_read_ack_stream_data(
         pFile = fopen(pFilename, "rb+");
         if (pFile) {
             (void)fseek(pFile, data->type.stream.fileStartPosition, SEEK_SET);
-            if (fwrite(octetstring_value(&data->fileData[0]),
+            if (fwrite(octetstring_value((BACNET_OCTET_STRING*)&data->fileData[0]),
                     octetstring_length(&data->fileData[0]), 1, pFile) != 1) {
 #if PRINT_ENABLED
                 fprintf(stderr, "Failed to write to %s (%lu)!\n", pFilename,
@@ -954,7 +954,7 @@ bool bacfile_read_ack_stream_data(
 }
 
 bool bacfile_read_ack_record_data(
-    uint32_t instance, BACNET_ATOMIC_READ_FILE_DATA *data)
+    uint32_t instance, const BACNET_ATOMIC_READ_FILE_DATA *data)
 {
     bool found = false;
     FILE *pFile = NULL;
@@ -978,7 +978,7 @@ bool bacfile_read_ack_record_data(
                 }
             }
             for (i = 0; i < data->type.record.RecordCount; i++) {
-                if (fwrite(octetstring_value(&data->fileData[i]),
+                if (fwrite(octetstring_value((BACNET_OCTET_STRING*)&data->fileData[i]),
                         octetstring_length(&data->fileData[i]), 1,
                         pFile) != 1) {
 #if PRINT_ENABLED