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>

test/bacnet/cov/src/main.c

@@ -21,7 +21,10 @@
  * @brief Test encode/decode API for unsigned 16b integers
  */
 int ccov_notify_decode_apdu(
-    uint8_t *apdu, unsigned apdu_len, uint8_t *invoke_id, BACNET_COV_DATA *data)
+    const uint8_t *apdu,
+    unsigned apdu_len,
+    uint8_t *invoke_id,
+    BACNET_COV_DATA *data)
 {
     int len = 0;
     unsigned offset = 0;
@@ -48,7 +51,7 @@ int ccov_notify_decode_apdu(
 }
 
 int ucov_notify_decode_apdu(
-    uint8_t *apdu, unsigned apdu_len, BACNET_COV_DATA *data)
+    const uint8_t *apdu, unsigned apdu_len, BACNET_COV_DATA *data)
 {
     int len = 0;
     unsigned offset = 0;
@@ -71,7 +74,7 @@ int ucov_notify_decode_apdu(
 }
 
 static int cov_subscribe_decode_apdu(
-    uint8_t *apdu,
+    const uint8_t *apdu,
     unsigned apdu_len,
     uint8_t *invoke_id,
     BACNET_SUBSCRIBE_COV_DATA *data)
@@ -100,7 +103,7 @@ static int cov_subscribe_decode_apdu(
 }
 
 static int cov_subscribe_property_decode_apdu(
-    uint8_t *apdu,
+    const uint8_t *apdu,
     unsigned apdu_len,
     uint8_t *invoke_id,
     BACNET_SUBSCRIBE_COV_DATA *data)
@@ -129,9 +132,10 @@ static int cov_subscribe_property_decode_apdu(
 }
 
 /* dummy function stubs */
-static void testCOVNotifyData(BACNET_COV_DATA *data, BACNET_COV_DATA *test_data)
+static void testCOVNotifyData(
+    const BACNET_COV_DATA *data, BACNET_COV_DATA *test_data)
 {
-    BACNET_PROPERTY_VALUE *value = NULL;
+    const BACNET_PROPERTY_VALUE *value = NULL;
     BACNET_PROPERTY_VALUE *test_value = NULL;
 
     zassert_equal(
@@ -170,7 +174,7 @@ static void testCOVNotifyData(BACNET_COV_DATA *data, BACNET_COV_DATA *test_data)
     }
 }
 
-static void testUCOVNotifyData(BACNET_COV_DATA *data)
+static void testUCOVNotifyData(const BACNET_COV_DATA *data)
 {
     uint8_t apdu[480] = { 0 };
     int len = 0, null_len = 0, apdu_len = 0;
@@ -190,7 +194,7 @@ static void testUCOVNotifyData(BACNET_COV_DATA *data)
     testCOVNotifyData(data, &test_data);
 }
 
-static void testCCOVNotifyData(uint8_t invoke_id, BACNET_COV_DATA *data)
+static void testCCOVNotifyData(uint8_t invoke_id, const BACNET_COV_DATA *data)
 {
     uint8_t apdu[480] = { 0 };
     int len = 0, null_len = 0, apdu_len = 0;
@@ -247,7 +251,8 @@ static void testCOVNotify(void)
 }
 
 static void testCOVSubscribeData(
-    BACNET_SUBSCRIBE_COV_DATA *data, BACNET_SUBSCRIBE_COV_DATA *test_data)
+    const BACNET_SUBSCRIBE_COV_DATA *data,
+    const BACNET_SUBSCRIBE_COV_DATA *test_data)
 {
     zassert_equal(
         test_data->subscriberProcessIdentifier,
@@ -272,7 +277,8 @@ static void testCOVSubscribeData(
 }
 
 static void testCOVSubscribePropertyData(
-    BACNET_SUBSCRIBE_COV_DATA *data, BACNET_SUBSCRIBE_COV_DATA *test_data)
+    const BACNET_SUBSCRIBE_COV_DATA *data,
+    const BACNET_SUBSCRIBE_COV_DATA *test_data)
 {
     testCOVSubscribeData(data, test_data);
     zassert_equal(
@@ -290,7 +296,8 @@ static void testCOVSubscribePropertyData(
 }
 
 static void
-testCOVSubscribeEncoding(uint8_t invoke_id, BACNET_SUBSCRIBE_COV_DATA *data)
+testCOVSubscribeEncoding(
+    uint8_t invoke_id, const BACNET_SUBSCRIBE_COV_DATA *data)
 {
     uint8_t apdu[480] = { 0 };
     int len = 0;
@@ -310,7 +317,7 @@ testCOVSubscribeEncoding(uint8_t invoke_id, BACNET_SUBSCRIBE_COV_DATA *data)
 }
 
 static void testCOVSubscribePropertyEncoding(
-    uint8_t invoke_id, BACNET_SUBSCRIBE_COV_DATA *data)
+    uint8_t invoke_id, const BACNET_SUBSCRIBE_COV_DATA *data)
 {
     uint8_t apdu[480] = { 0 };
     int len = 0;