Password strength & validation update, also allowing users to use special characters in passwords

[ricknjacky]

issue reference:- #22

Tasks done:-

• Updated the regex to allow special characters {even the non-native English ones}

• Used zxcbn for password strength estimation.

• Enhanced the UI for:-
  -1. strength estimation features of zxcvbn accordingly.
  -2. added a new feature for confirming the password entered.

• Allow users to signup only if both passwords match.

[NikhilM98]

There are some minor changes that need to be done to maintain the code quality.

[NikhilM98]

• https://github.com/NikhilM98/sugarizer-school-portal-server/pull/32/files#r644049332
• https://github.com/NikhilM98/sugarizer-school-portal-server/pull/32/files#r644156110
• https://github.com/NikhilM98/sugarizer-school-portal-server/pull/32/files#r644047170

Still needs to be resolved.