feat: support "kbcli backuprepo delete"

[zjx20]

Close #79.

[codecov-commenter]

Codecov Report

Attention: 13 lines in your changes are missing coverage. Please review.

Comparison is base (4a81fde) 42.92% compared to head (4031216) 43.00%.
Report is 1 commits behind head on main.

❗ Current head 4031216 differs from pull request most recent head bf9c6af. Consider uploading reports for the commit bf9c6af to get more accurate results

Files	Patch %	Lines
pkg/cmd/backuprepo/delete.go	67.50%	9 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #92      +/-   ##
==========================================
+ Coverage   42.92%   43.00%   +0.07%     
==========================================
  Files         223      224       +1     
  Lines       28626    28683      +57     
==========================================
+ Hits        12289    12335      +46     
- Misses      14811    14819       +8     
- Partials     1526     1529       +3     

Flag	Coverage Δ
unittests	43.00% <77.19%> (+0.07%)	⬆️

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