Add client specific config

[jkroepke]

What this PR does / why we need it

Which issue this PR fixes

(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

• fixes #

Special notes for your reviewer

Particularly user-facing changes

Checklist

Complete these before marking the PR as ready to review:

• DCO signed
• The PR title has a summary of the changes
• The PR body has a summary to reflect any significant (and particularly user-facing) changes introduced by this PR

[codecov]

Codecov Report

Attention: Patch coverage is 79.74684% with 16 lines in your changes missing coverage. Please review.

Project coverage is 84.06%. Comparing base (8a7ceb7) to head (92edb0e).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/config/validate.go	0.00%	6 Missing and 1 partial ⚠️
internal/openvpn/callbacks.go	79.31%	4 Missing and 2 partials ⚠️
cmd/daemon/root.go	50.00%	1 Missing and 1 partial ⚠️
internal/openvpn/client.go	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #316      +/-   ##
==========================================
- Coverage   84.37%   84.06%   -0.32%     
==========================================
  Files          50       50              
  Lines        2445     2491      +46     
==========================================
+ Hits         2063     2094      +31     
- Misses        251      262      +11     
- Partials      131      135       +4     

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