Issue #485: Fix linting

[nikosbosse]

Description

This PR closes #485

This PR fixes linting issues on the current development branch. It

• adds R files based on the vignettes to the files ignored by the linter (these are automatically generated based on the vignettes and always contain linting issues)
• fixes various linting issues across a large number of files.

Two single items stand out:

1. the function name interval_coverage_deviation_quantile is too long
2. the function name plot.scoringutils_available_forecasts is too long

We could simply change interval_coverage_deviation_quantile to interval_coverage_dev_quantile (exactly 30 chars long). An alternative would be to simply exclude the line from linting.
The second one is related to #403.

Update 1 I created a second PR for the name of plot.scoringutils_available_forecasts(), #511, which addresses #403
Update 2 I renamed the function to interval_coverage_dev_quantile

Checklist

• My PR is based on a package issue and I have explicitly linked it.
• I have included the target issue or issues in the PR title as follows: issue-number: PR title
• I have tested my changes locally.
• I have added or updated unit tests where necessary.
• I have updated the documentation if required.
• I have built the package locally and run rebuilt docs using roxygen2.
• My code follows the established coding standards and I have run lintr::lint_package() to check for style issues introduced by my changes.
• I have added a news item linked to this PR.
• I have reviewed CI checks for this PR and addressed them as far as I am able.

[codecov]

Codecov Report

Attention: 11 lines in your changes are missing coverage. Please review.

Comparison is base (55e5744) 81.21% compared to head (d2844d3) 81.21%.
Report is 3 commits behind head on develop.

Files	Patch %	Lines
R/metrics-quantile.R	65.51%	10 Missing ⚠️
R/metrics-sample.R	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #509   +/-   ##
========================================
  Coverage    81.21%   81.21%           
========================================
  Files           20       20           
  Lines         1725     1725           
========================================
  Hits          1401     1401           
  Misses         324      324           

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[seabbs]

Definitely looks better. I think shortening the name is fine. Still failing as its flagging all the lines that are new and don't have test coverage.

[nikosbosse]

I think I addressed all your comments. Are you happy for me to merge? In particular, should we address tests in a different PR, or would you prefer doing this now?

[seabbs]

LGTM