fix: allow getting resources with number as name

[phm07]

If the name of a user-named resource was numeric, it was impossible to Get it from its name, since a number would always be interpreted as an ID. This PR fixes this behavior on user-namable resources by continuing to check if a resource with the given idOrName exists even though the idOrName is numeric and no resource with the given ID was found.

See hetznercloud/cli#874

[codecov]

Codecov Report

Attention: Patch coverage is 92.30769% with 4 lines in your changes missing coverage. Please review.

Project coverage is 68.00%. Comparing base (51baf8d) to head (75b6ace).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
hcloud/image.go	50.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #571      +/-   ##
==========================================
+ Coverage   67.87%   68.00%   +0.12%     
==========================================
  Files          47       47              
  Lines        4912     4938      +26     
==========================================
+ Hits         3334     3358      +24     
- Misses       1170     1172       +2     
  Partials      408      408              

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[jooola]

I think the ISOs can be named by the customer, it is missing from this PR.