Add NODISCARD to all {Decode,Parse}[...](...) functions returning bool. Sort includes.

src/util/strencodings.cpp

@@ -263,7 +263,7 @@ std::string DecodeBase32(const std::string& str)
     return std::string((const char*)vchRet.data(), vchRet.size());
 }
 
-static bool ParsePrechecks(const std::string& str)
+NODISCARD static bool ParsePrechecks(const std::string& str)
 {
     if (str.empty()) // No empty string allowed
         return false;