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/ptransfer.c

@@ -15,7 +15,7 @@
 /* encode service */
 static int pt_encode_apdu(uint8_t *apdu,
     uint16_t max_apdu,
-    BACNET_PRIVATE_TRANSFER_DATA *private_data)
+    const BACNET_PRIVATE_TRANSFER_DATA *private_data)
 {
     int len = 0; /* length of each encoding */
     int apdu_len = 0; /* total length of the apdu, return value */
@@ -50,7 +50,7 @@ static int pt_encode_apdu(uint8_t *apdu,
 
 int ptransfer_encode_apdu(uint8_t *apdu,
     uint8_t invoke_id,
-    BACNET_PRIVATE_TRANSFER_DATA *private_data)
+    const BACNET_PRIVATE_TRANSFER_DATA *private_data)
 {
     int apdu_len = 0; /* total length of the apdu, return value */
     int len = 0;
@@ -70,7 +70,7 @@ int ptransfer_encode_apdu(uint8_t *apdu,
 }
 
 int uptransfer_encode_apdu(
-    uint8_t *apdu, BACNET_PRIVATE_TRANSFER_DATA *private_data)
+    uint8_t *apdu, const BACNET_PRIVATE_TRANSFER_DATA *private_data)
 {
     int apdu_len = 0; /* total length of the apdu, return value */
     int len = 0;
@@ -134,7 +134,7 @@ int ptransfer_error_encode_apdu(uint8_t *apdu,
     uint8_t invoke_id,
     BACNET_ERROR_CLASS error_class,
     BACNET_ERROR_CODE error_code,
-    BACNET_PRIVATE_TRANSFER_DATA *private_data)
+    const BACNET_PRIVATE_TRANSFER_DATA *private_data)
 {
     int apdu_len = 0; /* total length of the apdu, return value */
     int len = 0; /* length of the part of the encoding */
@@ -266,7 +266,7 @@ int ptransfer_error_decode_service_request(uint8_t *apdu,
 
 int ptransfer_ack_encode_apdu(uint8_t *apdu,
     uint8_t invoke_id,
-    BACNET_PRIVATE_TRANSFER_DATA *private_data)
+    const BACNET_PRIVATE_TRANSFER_DATA *private_data)
 {
     int len = 0; /* length of each encoding */
     int apdu_len = 0; /* total length of the apdu, return value */