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>

ports/arduino_uno/bvlc-arduino.c

@@ -54,12 +54,9 @@ static int bvlc_encode_bvlc_result(uint8_t *pdu, BACNET_BVLC_RESULT result_code)
  * @return Upon successful completion, returns the number of bytes sent.
  *  Otherwise, -1 shall be returned and errno set to indicate the error.
  */
-static int bvlc_send_mpdu(uint8_t *dest_addr, /* the destination address */
-
-    uint16_t *dest_port, /* the destination port */
-
+static int bvlc_send_mpdu(const uint8_t *dest_addr, /* the destination address */
+    const uint16_t *dest_port, /* the destination port */
     uint8_t *mtu, /* the data */
-
     uint16_t mtu_len)
 { /* amount of data to send  */
     /* assumes that the driver has already been initialized */
@@ -75,9 +72,8 @@ static int bvlc_send_mpdu(uint8_t *dest_addr, /* the destination address */
  * @param dest_addr - destination address
  * @param dest_port - destination port
  */
-static void bvlc_send_result(uint8_t *dest_addr,
-    uint16_t *dest_port, /* the destination address */
-
+static void bvlc_send_result(const uint8_t *dest_addr,
+    const uint16_t *dest_port, /* the destination address */
     BACNET_BVLC_RESULT result_code)
 {
     uint8_t mtu[BIP_MPDU_MAX] = { 0 };