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/lighting.h

@@ -91,25 +91,25 @@ extern "C" {
     BACNET_STACK_EXPORT
     int lighting_command_encode(
         uint8_t * apdu,
-        BACNET_LIGHTING_COMMAND * data);
+        const BACNET_LIGHTING_COMMAND * data);
     BACNET_STACK_EXPORT
     int lighting_command_encode_context(
         uint8_t * apdu,
         uint8_t tag_number,
-        BACNET_LIGHTING_COMMAND * value);
+        const BACNET_LIGHTING_COMMAND * value);
     BACNET_STACK_EXPORT
     int lighting_command_decode(
-        uint8_t * apdu,
+        const uint8_t * apdu,
         unsigned apdu_max_len,
         BACNET_LIGHTING_COMMAND * data);
     BACNET_STACK_EXPORT
     bool lighting_command_copy(
         BACNET_LIGHTING_COMMAND * dst,
-        BACNET_LIGHTING_COMMAND * src);
+        const BACNET_LIGHTING_COMMAND * src);
     BACNET_STACK_EXPORT
     bool lighting_command_same(
-        BACNET_LIGHTING_COMMAND * dst,
-        BACNET_LIGHTING_COMMAND * src);
+        const BACNET_LIGHTING_COMMAND * dst,
+        const BACNET_LIGHTING_COMMAND * src);
 
     BACNET_STACK_EXPORT
     bool lighting_command_from_ascii(
@@ -123,31 +123,31 @@ extern "C" {
 
     BACNET_STACK_EXPORT
     int xy_color_encode(uint8_t *apdu,
-        BACNET_XY_COLOR *value);
+        const BACNET_XY_COLOR *value);
     BACNET_STACK_EXPORT
     int xy_color_context_encode(
         uint8_t * apdu,
         uint8_t tag_number,
-        BACNET_XY_COLOR *value);
+        const BACNET_XY_COLOR *value);
     BACNET_STACK_EXPORT
     int xy_color_decode(
-        uint8_t *apdu,
+        const uint8_t *apdu,
         uint32_t apdu_size,
         BACNET_XY_COLOR *value);
     BACNET_STACK_EXPORT
     int xy_color_context_decode(
-        uint8_t *apdu,
+        const uint8_t *apdu,
         uint32_t apdu_size,
         uint8_t tag_number,
         BACNET_XY_COLOR *value);
     BACNET_STACK_EXPORT
     int xy_color_copy(
         BACNET_XY_COLOR *dst,
-        BACNET_XY_COLOR *src);
+        const BACNET_XY_COLOR *src);
     BACNET_STACK_EXPORT
     bool xy_color_same(
-        BACNET_XY_COLOR *value1,
-        BACNET_XY_COLOR *value2);
+        const BACNET_XY_COLOR *value1,
+        const BACNET_XY_COLOR *value2);
     BACNET_STACK_EXPORT
     void xy_color_set(
         BACNET_XY_COLOR *dst,
@@ -166,25 +166,25 @@ extern "C" {
     BACNET_STACK_EXPORT
     int color_command_encode(
         uint8_t * apdu,
-        BACNET_COLOR_COMMAND *address);
+        const BACNET_COLOR_COMMAND *address);
     BACNET_STACK_EXPORT
     int color_command_context_encode(
         uint8_t * apdu,
         uint8_t tag_number,
-        BACNET_COLOR_COMMAND *address);
+        const BACNET_COLOR_COMMAND *address);
     BACNET_STACK_EXPORT
-    int color_command_decode(uint8_t *apdu,
+    int color_command_decode(const uint8_t *apdu,
         uint16_t apdu_len,
         BACNET_ERROR_CODE *error_code,
         BACNET_COLOR_COMMAND *address);
     BACNET_STACK_EXPORT
     bool color_command_copy(
         BACNET_COLOR_COMMAND * dst,
-        BACNET_COLOR_COMMAND * src);
+        const BACNET_COLOR_COMMAND * src);
     BACNET_STACK_EXPORT
     bool color_command_same(
-        BACNET_COLOR_COMMAND * dst,
-        BACNET_COLOR_COMMAND * src);
+        const BACNET_COLOR_COMMAND * dst,
+        const BACNET_COLOR_COMMAND * src);
 
 #ifdef __cplusplus
 }