refactor: give annotations a value type

[lukasmetzner]

This is needed for an upcoming refactor, where a Load Balancer spec is built
from a corev1.Service object.

Additionally, we have a more stable doc generation, as we don't have to sync
the comment text with the targeted type.

[codecov]

Codecov Report

❌ Patch coverage is 87.96992% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.11%. Comparing base (6485324) to head (19944e7).

Files with missing lines	Patch %	Lines
tools/doc_generation.go	0.00%	11 Missing ⚠️
internal/hcops/load_balancer.go	91.83%	2 Missing and 2 partials ⚠️
hcloud/load_balancers.go	90.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1328      +/-   ##
==========================================
- Coverage   71.26%   70.11%   -1.16%     
==========================================
  Files          29       29              
  Lines        2875     2794      -81     
==========================================
- Hits         2049     1959      -90     
- Misses        635      643       +8     
- Partials      191      192       +1     

Flag	Coverage Δ
e2e	45.10% <73.77%> (+0.33%)	⬆️
unit	66.49% <87.21%> (-1.23%)	⬇️

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