Clean up the .gitignore file

[stefanhaller]

Globally ignoring all dot files and then making exceptions as needed to pull
files back in again is very error prone. It's better to explicitly exclude
everything we want to hide.

The reason why this came up is that I tried to look at the git history of one of
the files in .github/workflows/ using lazygit's path filtering feature, but it
didn't show up in the list of suggestions. It took me a while to realize that
that's because this list doesn't show git-ignored files. Now, .github/workflows/
wasn't really git-ignored because it was brought back by an exclamation mark
entry in the Exceptions section; but maybe the library we are using to get the
files doesn't handle these properly or something (I didn't further research
this).

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
Report missing for 528367b1	✅ ∅

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (528367b)	Report Missing	Report Missing	Report Missing
Head commit (f8865c4)	56995	49521	86.89%

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#4706)	0	0	∅ (not applicable)

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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Footnotes

1. Codacy didn't receive coverage data for the commit, or there was an error processing the received data. Check your integration for errors and validate that your coverage setup is correct. ↩