feat: Added endpoints for snapshot management

[SivaParvathi3112]

Description

• Added endpoints for snapshot management
• [GET] /machines/{id}/snapshots - Lists all snapshots of a virtual machine
• [POST] /machines/{id}/snapshots - Creates a new snapshot for a virtual machine
• [DELETE] /machines/{id}/snapshots/{snapshot_id} - Deletes a specific snapshot by its ID
• [POST] /machines/{id}/snapshots/{snapshot_id}/revert - Reverts the virtual machine to a specific snapshot
• [POST] /machines/{id}/snapshots/{snapshot_id}/switch - Switches the virtual machine to a specific snapshot (allows the --skip-resume param via the request body)

Part of #363

Type of change

• Documentation Change
• New feature (non-breaking change which adds functionality)

Checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have run tests that prove my fix is effective or that my feature works
• I have updated the CHANGELOG.md file accordingly

[sai-kumar-peddireddy]

LGTM