As ... is "(silently) deprecated". Presumably this means we should be giving correct, up-to-date suggestions, though.

The epitome of simplicity!

TokenStream::extend

Two new insta-stable impls in libproc_macro:

```rust
impl Extend<TokenTree> for TokenStream
impl Extend<TokenStream> for TokenStream
```

`proc_macro::TokenStream` already implements `FromIterator<TokenTree>` and `FromIterator<TokenStream>` so I elected to support the same input types for `Extend`.

**This commit reduces compile time of Serde derives by 60% (takes less than half as long to compile)** as measured by building our test suite:

```console
$ git clone https://github.com/serde-rs/serde
$ cd serde/test_suite
$ cargo check --tests --features proc-macro2/nightly
$ rm -f ../target/debug/deps/libtest_*.rmeta
$ time cargo check --tests --features proc-macro2/nightly
Before: 20.8 seconds
After: 8.6 seconds
```

r? @alexcrichton

Don't accept non-string literals for the format string in writeln

This is to improve diagnostics.

`println` and `eprintln` were already fixed by #52394.

Fixes #30143

Start adding an `aarch64-pc-windows-msvc` target

This commit adds the necessary definitions for target specs and such as well as
the necessary support in libstd to compile basic `aarch64-pc-windows-msvc`
binaries. The target is not currently built on CI, but it can be built locally
with:

    ./configure --target=aarch64-pc-windows-msvc --set rust.lld
    ./x.py build src/libstd --target aarch64-pc-windows-msvc

Currently this fails to build `libtest` due to a linker bug (seemingly in LLD?)
which hasn't been investigate yet. Otherwise though with libstd you can build a
hello world program (linked with LLD). I've not tried to execute it yet, but it
at least links!

Full support for this target is still a long road ahead, but this is hopefully a
good stepping stone to get started.

Points of note about this target are:

* Currently defaults to `panic=abort` as support is still landing in LLVM for
  SEH on AArch64.
* Currently defaults to LLD as a linker as I was able to get farther with it
  than I was with `link.exe`

For move errors, suggest match ergonomics instead of `ref`

Partially fixes issue #52423. Also makes errors and suggestions more consistent between move-from-place and move-from-value errors.

Limitations:
- Only the first pattern in a match arm can have a "consider removing this borrow operator" suggestion.
- Suggestions don't always compile as-is (see the TODOs in the test for details).

Sorry for the really long test. I wanted to make sure I handled every case I could think of, and it turned out there were a lot of them.

Questions:
- Is there any particular applicability I should set on those suggestions?
- Are the notes about the `Copy` trait excessive?

Various changes to `rustc_on_unimplemented`

- Add `from_method` and `from_desugaring` to formatting options
- Change wording of errors slightly