Clean up .gitignore

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.

This can be seen in the vendor directory, where we omitted a lot of files
accidentally (we'll fix that in the next commit). None of these were important,
so no harm done, but still.

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).

Author: stefanhaller

.gitignore

@@ -3,35 +3,21 @@
 # Logs
 *.log
 
-# Hidden
-.*
-!.codespellrc
-
 # Notes
 *.notes
 
 # Tests
 test/repos/repo
 coverage.txt
 
+# JetBrains stuff
+.idea/
+
 # Binaries
+.bin/
 lazygit
 lazygit.exe
 
-# Exceptions
-!.gitignore
-!.gitattributes
-!.goreleaser.yml
-!.golangci.yml
-!.circleci/
-!.github/
-!.vscode/
-!.devcontainer/
-
-# these are for our integration tests
-!.git_keep
-!.gitmodules_keep
-
 test/git_server/data
 
 test/_results/**