Added the initial script for the 40x example for backup and restore

[shailpujan88]

Description

This pull request adds a new script to the Vitess 401 example series, demonstrating how to create backups and restore tablets within a Vitess environment. The script initializes the necessary components, including the topology server, vtctld, and MySQL instances, before applying the schema and vschema to the specified keyspace. It introduces a new backup logic that identifies a replica tablet for backing up and implements a restore operation from the backup to another tablet. This comprehensive example serves as a practical guide for users to understand the backup and restore process in Vitess, ensuring data integrity and availability.

Related Issue(s)

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• "Backport to:" labels have been added if this change should be back-ported to release branches
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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.65%. Comparing base (8ba7607) to head (f11eb33).
Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16893      +/-   ##
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- Coverage   67.67%   67.65%   -0.02%     
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  Files        1584     1584              
  Lines      254368   254409      +41     
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- Hits       172139   172120      -19     
- Misses      82229    82289      +60     

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[github-actions]

This PR was closed because it has been stale for 7 days with no activity.

[mattlord]

LGTM! Just the nit about the copyright year after the new year.