Update protoc and Go dependencies

[rvolosatovs]

Summary

Regular dependency update
Refs #2417 (comment)

Changes

• Update protoc
• Update Go dependencies
• Adapt to upstream changes
• Refactor and fix web error middleware tests

Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, storage, configuration and CLI, according to the compatibility commitments in README.md. The target branch is set to master if the changes are fully compatible with existing API, database, configuration and CLI.
• Testing: The changes are covered with unit tests. The changes are tested manually as well.
• Documentation: Relevant documentation is added or updated.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.

[rvolosatovs]

blocking #2568

[htdvisser]

This isn't right. We need to render ErrorDetails as JSON, otherwise the console won't understand it.

[rvolosatovs]

Alright, as far as I understand the latest gogo protobuf version is not compatible with protobuf 1.4.x, so reverted the protobuf update.
I guess this particular issue can be fixed by just writing custom JSON encoding logic, but we never know what else might break, so better safe than sorry. (e.g. gogo/protobuf#686 gogo/protobuf#678 )

At least now we can actually see what breaks in the test.

[johanstokking]

Regression tests like this are fine with me

[htdvisser]

Looks good to me 👍