feat: improve missing argument error messages

[phm07]

This PR adds a custom Cobra command validator that outputs useful errors when positional arguments are missing during command execution. For example, such an error could look like this:

$ hcloud server describe   
hcloud server describe [options] <server>
                                  ^^^^^^
hcloud: expected argument server at position 1

Where previously it would look like this:

$ hcloud server describe
hcloud: accepts 1 arg(s), received 0

Additionally, if there are more arguments provided than necessary, the following error message will appear:

$ hcloud server describe arg1 arg2
hcloud server describe [options] <server>
                                          ^
hcloud: expected exactly 1 positional argument(s), but got 2

This is done by parsing the Use property of a Cobra command with a regular expression and then matching the corresponding missing arguments.

Fixes #700

[codecov]

Codecov Report

Attention: Patch coverage is 55.38462% with 29 lines in your changes are missing coverage. Please review.

Project coverage is 58.48%. Comparing base (ab6ef0e) to head (103f542).

Files	Patch %	Lines
internal/cmd/base/labels.go	0.00%	4 Missing ⚠️
internal/cmd/util/validation.go	90.32%	2 Missing and 1 partial ⚠️
internal/cmd/base/set_rdns.go	0.00%	2 Missing ⚠️
internal/cmd/base/update.go	0.00%	2 Missing ⚠️
internal/cmd/all/all.go	0.00%	1 Missing ⚠️
internal/cmd/base/cmd.go	0.00%	1 Missing ⚠️
internal/cmd/certificate/certificate.go	0.00%	1 Missing ⚠️
internal/cmd/datacenter/datacenter.go	0.00%	1 Missing ⚠️
internal/cmd/firewall/firewall.go	0.00%	1 Missing ⚠️
internal/cmd/floatingip/floatingip.go	0.00%	1 Missing ⚠️
... and 12 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #711      +/-   ##
==========================================
- Coverage   58.77%   58.48%   -0.29%     
==========================================
  Files         179      180       +1     
  Lines        6539     6497      -42     
==========================================
- Hits         3843     3800      -43     
  Misses       2088     2088              
- Partials      608      609       +1     

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[apricote]

Looks good to me :) Can be merged once #709 is in main :)