Overhaul the ErrorType trait

[sfackler]

Before this PR

The ErrorType trait had some significant limitations (like the inability to statically retrieve an error type's name string).

After this PR

==COMMIT_MSG== Overhauled the ErrorType trait. Its methods are now static, allowing easier comparison of the type of a serialized error. ==COMMIT_MSG==

When we work out #418, we can add some utility methods to turn a SerializableError back into a typed error.

Closes #339

[changelog-app[bot]]

Generate changelog in changelog/@unreleased

What do the change types mean?

• feature: A new feature of the service.
• improvement: An incremental improvement in the functionality or operation of the service.
• fix: Remedies the incorrect behaviour of a component of the service in a backwards-compatible way.
• break: Has the potential to break consumers of this service's API, inclusive of both Palantir services and external consumers of the service's API (e.g. customer-written software or integrations).
• deprecation: Advertises the intention to remove service functionality without any change to the operation of the service itself.
• manualTask: Requires the possibility of manual intervention (running a script, eyeballing configuration, performing database surgery, ...) at the time of upgrade for it to succeed.
• migration: A fully automatic upgrade migration task with no engineer input required.

Note: only one type should be chosen.

How are new versions calculated?

• ❗The break and manual task changelog types will result in a major release!
• 🐛 The fix changelog type will result in a minor release in most cases, and a patch release version for patch branches. This behaviour is configurable in autorelease.
• ✨ All others will result in a minor version release.

Type

• [ ] Feature
• [ ] Improvement
• [ ] Fix
• [x] Break
• [ ] Deprecation
• [ ] Manual task
• [ ] Migration

Description Overhauled the ErrorType trait. Its methods are now static, allowing easier comparison of the type of a serialized error.

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[stale[bot]]

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