Create Validator class

• Create Validation Utility methods

    import { Logger } from "@nestjs/common";
    import { ValidationException } from "./exception/validation-exception";

    export class Validator {

        private static readonly logger = new Logger(Validator.name);

        static isValidString(input: string, message: string) {
            if (input == null || input.trim() == "") {
                throw new ValidationException(message);
            }
        }

        static isValidNumber(input: number, message: string) {
            try {      
            if (input == null || input < 0 ) {
                    throw new ValidationException(message);
                }
            } catch (err) {
                throw new ValidationException(message);
            }
        }

        static isValidEmail(input: string, message: string) {
            if (input == null || input.trim() == "") {
                throw new ValidationException(message);
            }
        }
    }