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/win32/bip6.c

@@ -290,7 +290,7 @@ void bip6_get_my_address(BACNET_ADDRESS *addr)
  *
  * @param addr - network IPv6 address
  */
-bool bip6_set_addr(BACNET_IP6_ADDRESS *addr)
+bool bip6_set_addr(const BACNET_IP6_ADDRESS *addr)
 {
     return bvlc6_address_copy(&BIP6_Addr, addr);
 }
@@ -312,7 +312,7 @@ bool bip6_get_addr(BACNET_IP6_ADDRESS *addr)
  *
  * @return true if the BACnet/IPv6 address matches our own address
  */
-bool bip6_address_match_self(BACNET_IP6_ADDRESS *addr)
+bool bip6_address_match_self(const BACNET_IP6_ADDRESS *addr)
 {
     return !bvlc6_address_different(addr, &BIP6_Addr);
 }
@@ -322,7 +322,7 @@ bool bip6_address_match_self(BACNET_IP6_ADDRESS *addr)
  *
  * @param addr - network IPv6 address
  */
-bool bip6_set_broadcast_addr(BACNET_IP6_ADDRESS *addr)
+bool bip6_set_broadcast_addr(const BACNET_IP6_ADDRESS *addr)
 {
     return bvlc6_address_copy(&BIP6_Broadcast_Addr, addr);
 }
@@ -348,7 +348,7 @@ bool bip6_get_broadcast_addr(BACNET_IP6_ADDRESS *addr)
  * @return Upon successful completion, returns the number of bytes sent.
  *  Otherwise, -1 shall be returned and errno set to indicate the error.
  */
-int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
+int bip6_send_mpdu(const BACNET_IP6_ADDRESS *dest, const uint8_t *mtu, uint16_t mtu_len)
 {
     struct sockaddr_in6 bvlc_dest = { 0 };
     uint16_t addr16[8];
@@ -375,8 +375,8 @@ int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
     debug_print_ipv6("Sending MPDU->", &bvlc_dest.sin6_addr);
     /* Send the packet */
     return sendto(
-        BIP6_Socket, (char *)mtu, mtu_len, 0, (struct sockaddr *)&bvlc_dest,
-        sizeof(bvlc_dest));
+        BIP6_Socket, (const char *)mtu, mtu_len, 0,
+        (const struct sockaddr *)&bvlc_dest, sizeof(bvlc_dest));
 }
 
 /**
@@ -392,9 +392,9 @@ int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
  *  Otherwise, -1 shall be returned and errno set to indicate the error.
  */
 int bip6_send_pdu(
-    BACNET_ADDRESS *dest,
-    BACNET_NPDU_DATA *npdu_data,
-    uint8_t *pdu,
+    const BACNET_ADDRESS *dest,
+    const BACNET_NPDU_DATA *npdu_data,
+    const uint8_t *pdu,
     unsigned pdu_len)
 {
     return bvlc6_send_pdu(dest, npdu_data, pdu, pdu_len);