Improved dev environment (#2211)

* Improved dev env setup

* Cleanup duplicate checks

* Applied PR feedback

* Updated go.mod/go.sum

* go mod tidy

* Update .devcontainer/devcontainer.json

* Update pkg/http/server_test.go

Co-authored-by: Jan Larwig <jan@larwig.com>

* Create launch.json

* Update .devcontainer/Dockerfile

* Apply suggestions from code review

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Co-authored-by: Jan Larwig <jan@larwig.com>