Update User Creation

[TanmoySG]

This pull request includes several changes focused on enhancing user creation and privilege management in the wunderDB project. The most important changes include updating the user creation process to include metadata, modifying privilege names for clarity, and incorporating authentication handling.

Enhancements to user creation:

• internal/server/handlers/users.go: Updated the CreateUser function to parse metadata from the request body and handle user credentials via a new authentication handler.
• pkg/wdb/users.go: Modified the CreateUser method to accept metadata as a parameter and pass it to the user creation logic. [1] [2]
• pkg/wdb/wdb.go: Updated the Client interface to include metadata in the CreateUser method signature.

Privilege management improvements:

• documentation/README.md: Renamed privileges from addData, readData, updateData, and deleteData to addRecords, readRecords, updateRecords, and deleteRecords for better clarity.

Documentation update:

• documentation/README.md: Updated the user creation example to include metadata in the JSON body and added an Authorization header for better clarity.

Codebase maintenance:

• internal/filter/filters.go: Simplified the Filter function signature by removing redundant parentheses.
• internal/server/handlers/users.go: Removed the newUser struct, as it is no longer needed with the new user creation process.

These changes collectively improve the functionality and clarity of the user creation process and privilege management in the wunderDB project.