Add dump-shader-skp flag to flutter tools (#29258)

This is the accompanying change for https://github.com/flutter/engine/pull/8148 and it needs the engine PR to land first.

For https://github.com/flutter/flutter/issues/813

packages/flutter_tools/lib/src/device.dart

diff --git a/packages/flutter_tools/lib/src/device.dart b/packages/flutter_tools/lib/src/device.dart
index eb5ad6d..608a20f 100644
--- a/packages/flutter_tools/lib/src/device.dart
+++ b/packages/flutter_tools/lib/src/device.dart
@@ -371,6 +371,7 @@
     this.skiaDeterministicRendering = false,
     this.traceSkia = false,
     this.traceSystrace = false,
+    this.dumpSkpOnShaderCompilation = false,
     this.useTestFonts = false,
     this.verboseSystemLogs = false,
     this.observatoryPort,
@@ -384,6 +385,7 @@
       skiaDeterministicRendering = false,
       traceSkia = false,
       traceSystrace = false,
+      dumpSkpOnShaderCompilation = false,
       verboseSystemLogs = false,
       observatoryPort = null;
 
@@ -395,6 +397,7 @@
   final bool skiaDeterministicRendering;
   final bool traceSkia;
   final bool traceSystrace;
+  final bool dumpSkpOnShaderCompilation;
   final bool useTestFonts;
   final bool verboseSystemLogs;
   final int observatoryPort;