strings/json: Add string delimter match, and object create with vars methods

Add a function to check if there is an exact match a one string between
delimiters in another string.

Add a function that will create an ast_json object out of a list of
Asterisk variables. An excludes string can also optionally be passed
in.

Also, add a macro to make it easier to get object integers.

Change-Id: I5f34f18e102126aef3997f19a553a266d70d6226

include/asterisk/strings.h

@@ -400,6 +400,19 @@ void ast_copy_string(char *dst, const char *src, size_t size),
 }
 )
 
+/*!
+ * \brief Check if there is an exact match for 'needle' between delimiters in 'haystack'.
+ *
+ * \note This will skip extra leading spaces between delimiters.
+ *
+ * \param needle The string to search for
+ * \param haystack The string searched in
+ * \param delim The haystack delimiter
+ *
+ * \return True if an exact match for needle is in haystack, false otherwise
+ */
+int ast_in_delimited_string(const char *needle, const char *haystack, char delim);
+
 /*!
   \brief Build a string in a buffer, designed to be called repeatedly