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/dcc.c

@@ -144,7 +144,7 @@ bool dcc_set_status_duration(
 int dcc_apdu_encode(uint8_t *apdu,
     uint16_t timeDuration,
     BACNET_COMMUNICATION_ENABLE_DISABLE enable_disable,
-    BACNET_CHARACTER_STRING *password)
+    const BACNET_CHARACTER_STRING *password)
 {
     int len = 0; /* length of each encoding */
     int apdu_len = 0; /* total length of the apdu, return value */
@@ -187,7 +187,7 @@ size_t dcc_service_request_encode(uint8_t *apdu,
     size_t apdu_size,
     uint16_t timeDuration,
     BACNET_COMMUNICATION_ENABLE_DISABLE enable_disable,
-    BACNET_CHARACTER_STRING *password)
+    const BACNET_CHARACTER_STRING *password)
 {
     size_t apdu_len = 0; /* total length of the apdu, return value */
 
@@ -216,7 +216,7 @@ int dcc_encode_apdu(uint8_t *apdu,
     uint8_t invoke_id,
     uint16_t timeDuration,
     BACNET_COMMUNICATION_ENABLE_DISABLE enable_disable,
-    BACNET_CHARACTER_STRING *password)
+    const BACNET_CHARACTER_STRING *password)
 {
     int len = 0; /* length of each encoding */
     int apdu_len = 0; /* total length of the apdu, return value */
@@ -252,7 +252,7 @@ int dcc_encode_apdu(uint8_t *apdu,
  *
  * @return Bytes decoded, or BACNET_STATUS_ABORT or BACNET_STATUS_REJECT
  */
-int dcc_decode_service_request(uint8_t *apdu,
+int dcc_decode_service_request(const uint8_t *apdu,
     unsigned apdu_len_max,
     uint16_t *timeDuration,
     BACNET_COMMUNICATION_ENABLE_DISABLE *enable_disable,