Add SRv6 Testing Environment and Updated Vagrant Setup for VPP

[ziszat]

This pull request introduces improvements and additions to the FD.io VPP project, aiming to enhance developer experience and streamline SRv6-related testing and development. The key contributions include:

Automated VPP Virtual Machine Setup:

• Transition from deprecated Vagrant installation methods to a prepackaged VPP Vagrant box.

• Simplifies the process of setting up a functional VPP environment.

SRv6 Testing Environment:

• A new automated configuration for an example SRv6 topology using Vagrant.

Motivation

Challenges Addressed:

1. The previous Vagrant setup relied on obsolete installation methods, creating barriers for developers attempting to use VPP in virtualized environments.

2. Lack of a ready-to-use SRv6 test environment posed a challenge for developers exploring VPP's SRv6 features.

Proposed Solutions:

1. Use a prebuilt Vagrant box to eliminate dependency issues.

2. Provide an automated SRv6 topology to accelerate testing and development cycles.