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/service/h_cov.c

@@ -121,7 +121,7 @@ static void cov_address_remove_unused(void)
  *
  * @return index number 0..N, or -1 if unable to add
  */
-static int cov_address_add(BACNET_ADDRESS *dest)
+static int cov_address_add(const BACNET_ADDRESS *dest)
 {
     int index = -1;
     unsigned i = 0;
@@ -187,7 +187,9 @@ COVIncrement [4] REAL OPTIONAL
 */
 
 static int cov_encode_subscription(
-    uint8_t *apdu, int max_apdu, BACNET_COV_SUBSCRIPTION *cov_subscription)
+    uint8_t *apdu,
+    int max_apdu,
+    const BACNET_COV_SUBSCRIPTION *cov_subscription)
 {
     int len = 0;
     int apdu_len = 0;
@@ -323,8 +325,8 @@ void handler_cov_init(void)
     }
 }
 
-static bool cov_list_subscribe(BACNET_ADDRESS *src,
-    BACNET_SUBSCRIBE_COV_DATA *cov_data,
+static bool cov_list_subscribe(const BACNET_ADDRESS *src,
+    const BACNET_SUBSCRIBE_COV_DATA *cov_data,
     BACNET_ERROR_CLASS *error_class,
     BACNET_ERROR_CODE *error_code)
 {
@@ -333,7 +335,7 @@ static bool cov_list_subscribe(BACNET_ADDRESS *src,
     int first_invalid_index = -1;
     bool found = true;
     bool address_match = false;
-    BACNET_ADDRESS *dest = NULL;
+    const BACNET_ADDRESS *dest = NULL;
 
     /* unable to subscribe - resources? */
     /* unable to cancel subscription - other? */
@@ -717,8 +719,8 @@ void handler_cov_task(void)
     handler_cov_fsm();
 }
 
-static bool cov_subscribe(BACNET_ADDRESS *src,
-    BACNET_SUBSCRIBE_COV_DATA *cov_data,
+static bool cov_subscribe(const BACNET_ADDRESS *src,
+    const BACNET_SUBSCRIBE_COV_DATA *cov_data,
     BACNET_ERROR_CLASS *error_class,
     BACNET_ERROR_CODE *error_code)
 {