analyzer: Move the DevExp style guide doc to analysis_server

This is awkward as there are some packages which are co-developed like
analyzer_testing and analyzer_utilities. But broadly speaking, this
style guide is used for the "analysis-related" packages that the Dash
Developer Experience team maintains. So we can move it to live with the
other docs in pkg/analysis_server.

Change-Id: Ic94cfe1d16288ec707c96a42c7a18788e9f8b7d0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/435220
Reviewed-by: Paul Berry <[email protected]>
Commit-Queue: Samuel Rawlins <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: srawlins

pkg/analyzer/doc/implementation/coding_style.md renamed to pkg/analysis_server/doc/implementation/coding_style.md

@@ -1,10 +1,16 @@
 # Coding style
 
 This document is a place to record information about the coding style that's
-currently being used by the developers of the analyzer packages (the
-`analysis_server`, `analyzer`, `analyzer_plugin`, `analyzer_utilities`,
-`dartdoc`, `linter`, and `markdown` packages). As such, it's subject to change
-as the language evolves and as our experience dictates.
+currently being used by the Dash Developer Experience team for some static
+analysis packages (the `analysis_server`, `analysis_server_plugin`,
+`analyzer_plugin`, `analyzer_testing`, `analyzer_utilities`, and `linter`
+packages). As such, it's subject to change as the language evolves and as our
+experience dictates.
+
+Note that the `analyzer` package is developed by the Dart Model team, which
+follows a different coding style. The `analyzer_testing` and
+`analyzer_utilities` packages are developed jointly between the Dart Model and
+Dash Developer Experience teams.
 
 The document is divided into three main sections covering the coding styles we
 - have decided to follow,