feat(archive): Vex Archive

[JigyasuRajput]

This PR introduces a new feature that allows users to archive VEX data, which provides more context on the exploitability of vulnerabilities.

Description

The primary goal of this feature is to enhance the cve-bin-tool by enabling it to process and store VEX information. This will allow for more nuanced and accurate vulnerability assessments. The key additions are:

• VEX Archive Setup: Initializes the basic structure and setup for handling VEX data.
• JSON Report Parsing: Implements the logic to parse JSON-formatted VEX reports.
• VEX Archive Logic: Adds the core logic for archiving the VEX data.
• User Feedback: Provides feedback to the user after the new file is saved.
• Dry Run Mode: Includes a --dry-run mode to allow users to test the functionality without making permanent changes.
• Testing: Adds comprehensive tests for the new VEX archive functionality.
• Documentation: Includes documentation for the new VEX archive feature.