[Admin] connect auth helpers to the sidebar

[elia]

Summary

Checklist

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• I have written a thorough PR description.
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[codecov]

Codecov Report

Merging #5293 (64ebbed) into nebulab/admin (1b08fed) will increase coverage by 0.00%.
Report is 11 commits behind head on nebulab/admin.
The diff coverage is 100.00%.

@@              Coverage Diff               @@
##           nebulab/admin    #5293   +/-   ##
==============================================
  Coverage          88.56%   88.56%           
==============================================
  Files                599      599           
  Lines              14563    14565    +2     
==============================================
+ Hits               12897    12899    +2     
  Misses              1666     1666           

Files Changed	Coverage Δ
...nts/solidus_admin/sidebar/account_nav/component.rb	100.00% <100.00%> (ø)
admin/app/controllers/solidus_admin/auth.rb	100.00% <100.00%> (ø)
...n/app/controllers/solidus_admin/base_controller.rb	100.00% <100.00%> (ø)
admin/lib/solidus_admin/configuration.rb	100.00% <100.00%> (ø)
admin/lib/solidus_admin/preview.rb	93.33% <100.00%> (+1.02%)	⬆️

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