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/unit/bacnet/bacerror/src/fakes/bacdcode.c

@@ -16,7 +16,7 @@ DEFINE_FAKE_VALUE_FUNC(int, decode_tag_number, uint8_t *, uint8_t *);
 DEFINE_FAKE_VALUE_FUNC(int, bacnet_tag_number_decode, uint8_t *, uint32_t, uint8_t *);
 #endif
 DEFINE_FAKE_VALUE_FUNC(
-    int, decode_tag_number_and_value, uint8_t *, uint8_t *, uint32_t *);
+    int, decode_tag_number_and_value, const uint8_t *, uint8_t *, uint32_t *);
 #if 0
 DEFINE_FAKE_VALUE_FUNC(int, bacnet_tag_number_and_value_decode, uint8_t *, uint32_t, uint8_t *, uint32_t *);
 DEFINE_FAKE_VALUE_FUNC(bool, decode_is_opening_tag_number, uint8_t *, uint8_t);
@@ -86,7 +86,7 @@ DEFINE_FAKE_VALUE_FUNC(int, bacnet_signed_application_decode, uint8_t *, uint16_
 DEFINE_FAKE_VALUE_FUNC(int, bacnet_enumerated_decode, uint8_t *, uint16_t, uint32_t, uint32_t *);
 DEFINE_FAKE_VALUE_FUNC(int, bacnet_enumerated_context_decode, uint8_t *, uint16_t, uint8_t, uint32_t *);
 #endif
-DEFINE_FAKE_VALUE_FUNC(int, decode_enumerated, uint8_t *, uint32_t, uint32_t *);
+DEFINE_FAKE_VALUE_FUNC(int, decode_enumerated, const uint8_t *, uint32_t, uint32_t *);
 #if 0
 DEFINE_FAKE_VALUE_FUNC(int, decode_context_enumerated, uint8_t *, uint8_t, uint32_t *);
 DEFINE_FAKE_VALUE_FUNC(int, encode_bacnet_enumerated, uint8_t *, uint32_t);

test/unit/bacnet/bacerror/src/fakes/bacdcode.h

@@ -29,7 +29,7 @@ DECLARE_FAKE_VALUE_FUNC(int, decode_tag_number, uint8_t *, uint8_t *);
 DECLARE_FAKE_VALUE_FUNC(int, bacnet_tag_number_decode, uint8_t *, uint32_t, uint8_t *);
 #endif
 DECLARE_FAKE_VALUE_FUNC(
-    int, decode_tag_number_and_value, uint8_t *, uint8_t *, uint32_t *);
+    int, decode_tag_number_and_value, const uint8_t *, uint8_t *, uint32_t *);
 #if 0
 DECLARE_FAKE_VALUE_FUNC(int, bacnet_tag_number_and_value_decode, uint8_t *, uint32_t, uint8_t *, uint32_t *);
 DECLARE_FAKE_VALUE_FUNC(bool, decode_is_opening_tag_number, uint8_t *, uint8_t);
@@ -100,7 +100,7 @@ DECLARE_FAKE_VALUE_FUNC(int, bacnet_enumerated_decode, uint8_t *, uint16_t, uint
 DECLARE_FAKE_VALUE_FUNC(int, bacnet_enumerated_context_decode, uint8_t *, uint16_t, uint8_t, uint32_t *);
 #endif
 DECLARE_FAKE_VALUE_FUNC(
-    int, decode_enumerated, uint8_t *, uint32_t, uint32_t *);
+    int, decode_enumerated, const uint8_t *, uint32_t, uint32_t *);
 #if 0
 DECLARE_FAKE_VALUE_FUNC(int, decode_context_enumerated, uint8_t *, uint8_t, uint32_t *);
 DECLARE_FAKE_VALUE_FUNC(int, encode_bacnet_enumerated, uint8_t *, uint32_t);

test/unit/bacnet/bacerror/src/main.c

@@ -93,7 +93,7 @@ struct decode_tag_number_and_value_custom_fake_context {
 };
 
 static int decode_tag_number_and_value_custom_fake(
-    uint8_t *apdu, uint8_t *tag_number, uint32_t *value)
+    const uint8_t *apdu, uint8_t *tag_number, uint32_t *value)
 {
     RETURN_HANDLED_CONTEXT(decode_tag_number_and_value,
         struct decode_tag_number_and_value_custom_fake_context,
@@ -125,7 +125,7 @@ struct decode_enumerated_custom_fake_context {
 };
 
 static int decode_enumerated_custom_fake(
-    uint8_t *apdu, uint32_t len_value, uint32_t *value)
+    const uint8_t *apdu, uint32_t len_value, uint32_t *value)
 {
     RETURN_HANDLED_CONTEXT(decode_enumerated,
         struct decode_enumerated_custom_fake_context,