Fix: Removed Unused code

[cs-raj]

This PR removes unused code from the @contentstack/cli-auth package to improve code maintainability and reduce technical debt. The changes include removal of unused validation methods and related test files.

Changes

Code Removal

• Removed unused methods from auth-handler.ts:

  • validateAuthtoken() method

• Removed unused methods from mfa-handler.ts:

  • getManualMFACode() method
  • isValidMFACode() method

• Deleted entire tokens-validation.ts file:

  • Removed validateEnvironment() function
  • Removed validateAPIKey() function
  • Removed export from utils/index.ts

• Removed related test files:

  • Deleted test/unit/tokens-validation.test.ts
  • Removed test stubs and references from test/unit/commands/tokens-add.test.ts

Version Updates

• Bumped @contentstack/cli-auth version from 1.7.2 to 1.7.3
• Updated dependency references in:
  • packages/contentstack-export/package.json
  • packages/contentstack/package.json

Impact

• No breaking changes: All removed code was unused and not referenced elsewhere in the codebase
• Reduced bundle size: Removal of unused code reduces the package size
• Improved maintainability: Cleaner codebase with less dead code to maintain