Guide user when they try to use old Borg1 style commands.

[gmatht]

Description

This implements/fixes #9545 parts 1, 3, 6, 8 (Other parts left unimplemented as TW suggested they add more complexity than they are worth). This pull request supercedes #9541

Checklist

• PR is against master (or maintenance branch if only applicable there)
• New code has tests and docs where appropriate
• Tests pass (run tox or the relevant test subset)
• Commit messages are clean and reference related issues

[codecov]

Codecov Report

❌ Patch coverage is 86.11111% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.11%. Comparing base (da0a2ff) to head (b3a573a).
⚠️ Report is 18 commits behind head on master.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/borg/archiver/__init__.py	86.11%	8 Missing and 7 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9656      +/-   ##
==========================================
+ Coverage   83.08%   83.11%   +0.02%     
==========================================
  Files          90       90              
  Lines       15653    15761     +108     
  Branches     2356     2386      +30     
==========================================
+ Hits        13006    13099      +93     
- Misses       1887     1895       +8     
- Partials      760      767       +7     

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