Use annotate-snippet as default emitter on stable
This is implementation of https://github.com/rust-lang/rust/issues/149932
Now, after MCP was accepted, we can use annotate-snippet as default emitter for errors, that means that we not longer need of previous emitter, so this PR removed previous emitter and makes annotate-snippet new default one both on stable and nightly
(this PR does not remove a code of previous emitter it just removes a `Default` option of `HumanReadableErrorType` enum, and keeping only `HumanReadableErrorType::AnnotateSnippet` as it now uses by default)
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