provide a weak print char impl

src/fsfw_hal/common/CMakeLists.txt

@@ -1 +1,3 @@
 add_subdirectory(gpio)
+
+target_sources(${LIB_FSFW_NAME} PRIVATE printChar.c)

src/fsfw_hal/common/printChar.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdbool.h>
+
+void __attribute__((weak)) printChar(const char* character, bool errStream) {
+  if (errStream) {
+    fprintf(stderr, "%c", *character);
+  } else {
+    printf("%c", *character);
+  }
+}