CLI-1631: validating backup link before importing database

[kalindi-adhiya]

Motivation

Fixes #NNN

Proposed changes

Alternatives considered

Testing steps

1. Follow the contribution guide to set up your development environment or download a pre-built acli.phar for this PR.
2. If running from source, clear the kernel cache to pick up new and changed commands: ./bin/acli ckc
3. Check for regressions: (add specific steps for this pr)
4. Check new functionality: (add specific steps for this pr)

[codecov]

Codecov Report

❌ Patch coverage is 92.85714% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.27%. Comparing base (342be01) to head (4433969).

Files with missing lines	Patch %	Lines
src/Command/Pull/PullCommandBase.php	92.85%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1958      +/-   ##
============================================
- Coverage     92.27%   92.27%   -0.01%     
- Complexity     1916     1932      +16     
============================================
  Files           122      122              
  Lines          6994     7039      +45     
============================================
+ Hits           6454     6495      +41     
- Misses          540      544       +4     

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