Log Message:
rust-analyzer: update to 0.0.2021.12.27.

2021.12.27

11122: Remove note about alpha status from vscode extension
description

2021.12.20

11060: minor: Bump deps

2021.12.13

10995: internal: switch from trait-based TokenSource to simple
struct of arrays

cc #10765

The idea here is to try to simplify the interface as best as we
can. The original trait-based approach is a bit over-engineered
and hard to debug. Here, we replace callback with just data. The
next PR in series will replace the output `TreeSink` trait with
data as well.

The biggest drawback here is that we now require to materialize
all parser's input up-front. This is a bad fit for macro by example:
when you parse `$e:expr`, you might consume only part of the input.
However, today's trait-based solution doesn't really help -- we
were already materializing the whole thing! So, let's keep it
simple!