Gets a claim by key from a l8w8jwt_claim array.
@param claims The array to look in.
@param claims_count The claims array size.
@param key The claim key (e.g. "sub") to look for.
@param key_length The claim key's string length.
@return The found claim; <code>NULL</code> if no such claim was found in the array.
Gets a claim by key from a l8w8jwt_claim array. @param claims The array to look in. @param claims_count The claims array size. @param key The claim key (e.g. "sub") to look for. @param key_length The claim key's string length. @return The found claim; <code>NULL</code> if no such claim was found in the array.