Fail typecheck if we encounter a bogus break

Lone breaks outside of loops create errors in the
loop check pass but as they are not fatal,
compilation continues.

MIR building code assumes all HIR break statements
to point to valid locations and fires ICEs if this
assumption is violated. In normal compilation,
this causes no issues, as code apparently prevents
MIR from being built if errors are present.

However, before that, typecheck runs and with it
MIR const eval. Here we operate differently
from normal compilation: it doesn't check for any
errors except for type checker ones and then
directly builds the MIR.

This constellation causes an ICE-on-error if
bogus break statements are being put into array
length expressions.

This commit fixes this ICE by letting typecheck
fail if bogus break statements are encountered.
This way, MIR const eval fails cleanly with a
type check error.

Fixes rust-lang#50576
Fixes rust-lang#50581

Rollup of 11 pull requests

Successful merges:

 - #50987 (Underline multiple suggested replacements in the same line)
 - #51014 (Add documentation about env! second argument)
 - #51034 (Remove unused lowering field and method)
 - #51047 (Use AllFacts from polonius-engine)
 - #51048 (Add more missing examples for Formatter)
 - #51056 (Mention and use `Once::new` instead of `ONCE_INIT`)
 - #51059 (What does an expression look like, that consists only of special characters?)
 - #51065 (Update nomicon link in transmute docs)
 - #51067 (Add inner links in documentation)
 - #51070 (Fail typecheck if we encounter a bogus break)
 - #51073 (Rename TokenStream::empty to TokenStream::new)

Failed merges: