Enhance JWT Token Management

[RishiVT2004]

Fixed Issue #99

Changes Made to the codebase

1. Added Middleware for Environment Variable Validation

Introduced a checkKey middleware function to validate the presence of ACCESS_TOKEN_SECRET in environment variables
and assign it to req.Key for use in subsequent functions.

2. Refactored generateAccessToken Function

Improved error handling with specific messages for token generation failure and server errors.
Returned the token as a JSON object with a clear key.

3. Improved decodeAccessToken Function

Streamlined error checking for the authorization header.
Removed redundant checks and ensured the function handles decoding the token appropriately.
Returned error messages with appropriate status codes for missing authorization headers, token decoding failures, and invalid or expired tokens.

4. Consistent Error Responses

Ensured that all error responses are formatted consistently with proper status codes and messages.

[RishiVT2004]

@Harshdev098 please review this pr and add necessary tags(hacktoberfest and gssoc)

[Harshdev098]

Its giving error, I think its because you have changed the parameters of the generateAccessToken and decodeAccessToken , and its very overwhelming to update these functions in every files, if there is any other method to add the middleware you can go with it, or discard the changes done for setting the middleware checkKey because i think its not that necessary

[Harshdev098]

OR you can update the functions in the files

[RishiVT2004]

@Harshdev098 i think refactoring the code will cause too much issue in the future , let me try to simplify and change the code according to your needs

[Harshdev098]

Yah, right

[RishiVT2004]

@Harshdev098 check if this is good enough or not and let me know