[VPAT-51] fix: update workspace invitation flow to use token for validation

[dheeru0198]

Description

• Modified the invite link to include a token for enhanced security.
• Updated the WorkspaceJoinEndpoint to validate the token instead of the email.
• Adjusted the workspace invitation task to generate links with the token.
• Refactored the frontend to handle token in the invitation process.

Type of Change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] Feature (non-breaking change which adds functionality)
• [x] Improvement (change that would cause existing functionality to not work as expected)
• [ ] Code refactoring
• [ ] Performance improvements
• [ ] Documentation update

Screenshots and Media (if applicable)

Test Scenarios

References

Summary by CodeRabbit

• Refactor
  • Updated workspace invitation system to use token-based validation in place of email-based validation
  • Invitation URLs now include a unique token parameter for workspace joins

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