Add restriction to username

[Asoul]

Username without restriction may caused future problems, may add name field for another usage

[Asoul]

• username cannot be longer than 20 characters
• alphabet + numeric + some characters (underscore, hyphen, dot)
• no continuous symbol, starts or ends with
• display with case, but check with all lowercase

[Asoul]

• [x] Show restrict rule and validate in frontend