fix: won't panic on error handler validation failure

[squakez]

Introduced a validation for each kind of error handler.

With this PR we make sure that every error handler type is validated against the expected configuration. Validate() func need to be configured for each type according the logic required for it (in this case it seems only the sink requires some validation).

Closes #3586

Release Note

fix: won't panic on error handler validation failure

[squakez]

@essobedo with this one we should take care of providing the expected validation logic for each error handler type and fail during parse. It's a bit different on the first work you did on #3595, if you want to give a look.

[essobedo]

Really nice 👍