Add log error codes and map to documentation

Overview

After using Vector and encountering a few errors I think it would be beneficial to map known errors to codes / specific documentation takes. For example:

ERROR vector::topology: Configuration error: Source "in": data_dir option required, but not given here or globally

It'd be nice if we could add something like:

ERROR vector::topology: Configuration error: Source "in": data_dir option required, but not given here or globally. See https://docs.vector.dev/errors/abcd1234

Or something similar. This page would talk about the error and how to resolve it.

Ideas

One idea would be to parse this from the code itself and autogenerate the error pages as a result. I'm unsure how easy this would be, but it seems like https://github.com/timberio/vector/issues/543 makes this easier / possible.

Shaping

Before we begin work we should audit all of the messages and create a checkbox task list for each one. This includes updating the error message as well as the associated documentation page. I'd also like to agree on how this will work exactly, especially if we are able to auto-generate pages for the error messages.

Start by reviewing issue #543 and auditing the project's existing error messages, as requested in the shaping notes. Define and agree on the error-code and documentation approach before implementation. Done means the messages have an agreed mapping, a checkbox task list, updated error output, and corresponding documentation pages.