Enhancement: delete pages PDF action

[shamoon]

Proposed change

I think this should be the last of these. Hardest part was deciding the UI, went with a visual solution in the end. Like rotate, this modifies the original.

Closes #528

Type of change

• Bug fix: non-breaking change which fixes an issue.
• New feature / Enhancement: non-breaking change which adds functionality. Please read the important note above.
• Breaking change: fix or feature that would cause existing functionality to not work as expected.
• Documentation only.
• Other. Please explain:

Checklist:

• I have read & agree with the contributing guidelines.
• If applicable, I have included testing coverage for new code in this PR, for backend and / or front-end changes.
• If applicable, I have tested my code for new features & regressions on both mobile & desktop devices, using the latest version of major browsers.
• If applicable, I have checked that all tests pass, see documentation.
• I have run all pre-commit hooks, see documentation.
• I have made corresponding changes to the documentation as needed.
• I have checked my modifications for any breaking changes.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.21%. Comparing base (2116964) to head (b13a68c).

❗ Current head b13a68c differs from pull request most recent head 4f4765c

Please upload reports for the commit 4f4765c to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #6772      +/-   ##
==========================================
+ Coverage   97.19%   97.21%   +0.01%     
==========================================
  Files         436      438       +2     
  Lines       17981    18065      +84     
  Branches     1440     1498      +58     
==========================================
+ Hits        17477    17561      +84     
+ Misses        504      501       -3     
- Partials        0        3       +3     

Flag	Coverage Δ
backend	95.89% <100.00%> (+0.01%)	⬆️
frontend	98.64% <100.00%> (+<0.01%)	⬆️

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