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/wp.c

@@ -37,7 +37,7 @@
  * @return number of bytes encoded, or zero if unable to encode
  */
 size_t writeproperty_apdu_encode(
-    uint8_t *apdu, BACNET_WRITE_PROPERTY_DATA *data)
+    uint8_t *apdu, const BACNET_WRITE_PROPERTY_DATA *data)
 {
     size_t apdu_len = 0; /* total length of the apdu, return value */
     size_t len = 0; /* total length of the apdu, return value */
@@ -100,7 +100,7 @@ size_t writeproperty_apdu_encode(
  * @return number of bytes encoded, or zero if unable to encode or too large
  */
 size_t writeproperty_service_request_encode(
-    uint8_t *apdu, size_t apdu_size, BACNET_WRITE_PROPERTY_DATA *data)
+    uint8_t *apdu, size_t apdu_size, const BACNET_WRITE_PROPERTY_DATA *data)
 {
     size_t apdu_len = 0; /* total length of the apdu, return value */
 
@@ -136,7 +136,7 @@ size_t writeproperty_service_request_encode(
  * @return Bytes encoded
  */
 int wp_encode_apdu(
-    uint8_t *apdu, uint8_t invoke_id, BACNET_WRITE_PROPERTY_DATA *wpdata)
+    uint8_t *apdu, uint8_t invoke_id, const BACNET_WRITE_PROPERTY_DATA *wpdata)
 {
     int apdu_len = 0; /* total length of the apdu, return value */
     int len = 0; /* total length of the apdu, return value */
@@ -184,7 +184,9 @@ int wp_encode_apdu(
  * @return number of bytes decoded, or #BACNET_STATUS_ERROR
  */
 int wp_decode_service_request(
-    uint8_t *apdu, unsigned apdu_size, BACNET_WRITE_PROPERTY_DATA *wpdata)
+    const uint8_t *apdu,
+    unsigned apdu_size,
+    BACNET_WRITE_PROPERTY_DATA *wpdata)
 {
     int len = 0;
     int apdu_len = 0;
@@ -304,7 +306,7 @@ int wp_decode_service_request(
  * @return true if the expected tag matches the value tag
  */
 bool write_property_type_valid(BACNET_WRITE_PROPERTY_DATA *wp_data,
-    BACNET_APPLICATION_DATA_VALUE *value,
+    const BACNET_APPLICATION_DATA_VALUE *value,
     uint8_t expected_tag)
 {
     /* assume success */
@@ -330,7 +332,7 @@ bool write_property_type_valid(BACNET_WRITE_PROPERTY_DATA *wp_data,
  * @return true if the character string value is valid
  */
 bool write_property_string_valid(BACNET_WRITE_PROPERTY_DATA *wp_data,
-    BACNET_APPLICATION_DATA_VALUE *value,
+    const BACNET_APPLICATION_DATA_VALUE *value,
     size_t len_max)
 {
     bool valid = false;
@@ -387,7 +389,7 @@ bool write_property_string_valid(BACNET_WRITE_PROPERTY_DATA *wp_data,
  * @return true if the character string value is valid
  */
 bool write_property_empty_string_valid(BACNET_WRITE_PROPERTY_DATA *wp_data,
-    BACNET_APPLICATION_DATA_VALUE *value,
+    const BACNET_APPLICATION_DATA_VALUE *value,
     size_t len_max)
 {
     bool valid = false;