refactor(xod-arduino, workspace): replace platform-dependent dtostrf with dtoa and move shared formatters.cpp into cpplib directory and rename it

cpplib/catch2utils/XStringFormat.inl

@@ -0,0 +1,43 @@
+/**
+ * This file makes Catch2 show failed tests properly for the XString type.
+ * E.G.
+ * "some" == "something"
+ * instead of
+ * {?} == {?}
+ *
+ * Catch2 string conversion docs:
+ * https://github.com/catchorg/Catch2/blob/master/docs/tostring.md
+ */
+
+template <typename T>
+struct XodStringMaker {
+    static std::string convert(T value) {
+        size_t len = length(value) + 2;
+        std::string str(len, '\0');
+        size_t strPos = 1;
+
+        str[0] = '"';
+        str[len - 1] = '"';
+
+        for (auto it = value.iterate(); it; ++it) {
+            str[strPos++] = *it;
+        }
+        return str;
+    }
+};
+
+namespace Catch {
+template <>
+struct StringMaker<xod::XString> {
+    static std::string convert(xod::XString value) {
+        return XodStringMaker<xod::XString>::convert(value);
+    }
+};
+
+template <>
+struct StringMaker<xod::XStringCString> {
+    static std::string convert(xod::XStringCString value) {
+        return XodStringMaker<xod::XStringCString>::convert(value);
+    }
+};
+}