Add release notes for DevTools 2.51.1 (#12659)

Add release notes for the 2.51.1 hotfix version of DevTools. This is
version of DevTools that is going out with Flutter 3.38.

Includes the release notes for 2.51.0 along with the release notes for
the cherry-picks included in 2.51.1 (see
flutter/devtools@v2.51.0...v2.51.1)

Author: elliette

src/content/tools/devtools/release-notes/release-notes-2.51.1.md

@@ -0,0 +1,47 @@
+---
+title: DevTools 2.51.1 release notes
+shortTitle: 2.51.1 release notes
+breadcrumb: 2.51.1
+showToc: false
+---
+
+The 2.51.1 release of the Dart and Flutter DevTools
+includes the following changes among other general improvements.
+To learn more about DevTools, check out the
+[DevTools overview](/tools/devtools/overview).
+
+## General updates
+
+- Flutter beta channel users were opted into the DevTools-on-Wasm experiment.
+  All other users can still enable the Wasm-compiled DevTools from the settings
+  dialog. - [#9455](https://github.com/flutter/devtools/pull/9455)
+- Added a horizontal scrollbar to data tables to help with navigation. -
+  [#9482](https://github.com/flutter/devtools/pull/9482)
+- Made it possible to resize data table columns by dragging the header separators. -
+  [#9485](https://github.com/flutter/devtools/pull/9485)
+
+## Inspector updates
+
+- Fixed an issue where selecting a widget with the Inspector would open the
+  widget definition file instead of the user's project file. -
+  [#176530](https://github.com/flutter/flutter/pull/176530)
+
+## Network profiler updates
+
+- Fixed layout of the "error count" badge in the tab name. -
+  [#9470](https://github.com/flutter/devtools/pull/9470)
+- Fixed display of "Response Headers" and "Request Headers" when there are no
+  headers. - [#9492](https://github.com/flutter/devtools/pull/9492)
+- Added a banner to clearly indicate when DevTools is not logging network
+  requests. - [#9495](https://github.com/flutter/devtools/pull/9495)
+
+## VS Code updates
+
+- Fixed issue preventing shortcuts like `Cmd`+`C` and `Cmd`+`V` from working when DevTools was
+  embedded inside VS Code on macOS. -
+  [#9472](https://github.com/flutter/devtools/pull/9472)
+
+## Full commit history
+
+To find a complete list of changes in this release, check out the
+[DevTools git log](https://github.com/flutter/devtools/tree/v2.51.1).