Add ErrorGuaranteed to Recovered::Yes and use it more.

The starting point for this was identical comments on two different
fields, in `ast::VariantData::Struct` and `hir::VariantData::Struct`:
```
    // FIXME: investigate making this a `Option<ErrorGuaranteed>`
    recovered: bool
```
I tried that, and then found that I needed to add an `ErrorGuaranteed`
to `Recovered::Yes`. Then I ended up using `Recovered` instead of
`Option<ErrorGuaranteed>` for these two places and elsewhere, which
required moving `ErrorGuaranteed` from `rustc_parse` to `rustc_ast`.

This makes things more consistent, because `Recovered` is used in more
places, and there are fewer uses of `bool` and
`Option<ErrorGuaranteed>`. And safer, because it's difficult/impossible
to set `recovered` to `Recovered::Yes` without having emitted an error.

compiler/rustc_builtin_macros/src/format.rs

@@ -7,14 +7,13 @@ use rustc_ast::{token, StmtKind};
 use rustc_ast::{
     Expr, ExprKind, FormatAlignment, FormatArgPosition, FormatArgPositionKind, FormatArgs,
     FormatArgsPiece, FormatArgument, FormatArgumentKind, FormatArguments, FormatCount,
-    FormatDebugHex, FormatOptions, FormatPlaceholder, FormatSign, FormatTrait,
+    FormatDebugHex, FormatOptions, FormatPlaceholder, FormatSign, FormatTrait, Recovered,
 };
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{Applicability, Diag, MultiSpan, PResult, SingleLabelManySpans};
 use rustc_expand::base::*;
 use rustc_lint_defs::builtin::NAMED_ARGUMENTS_USED_POSITIONALLY;
 use rustc_lint_defs::{BufferedEarlyLint, BuiltinLintDiag, LintId};
-use rustc_parse::parser::Recovered;
 use rustc_parse_format as parse;
 use rustc_span::symbol::{Ident, Symbol};
 use rustc_span::{BytePos, ErrorGuaranteed, InnerSpan, Span};
@@ -112,7 +111,7 @@ fn parse_args<'a>(ecx: &ExtCtxt<'a>, sp: Span, tts: TokenStream) -> PResult<'a,
                         _ => return Err(err),
                     }
                 }
-                Ok(Recovered::Yes) => (),
+                Ok(Recovered::Yes(_)) => (),
                 Ok(Recovered::No) => unreachable!(),
             }
         }