Added Doxyfile. (#9632)

Added Doxyfile.

.gitignore

@@ -21,3 +21,5 @@ Thumbs.db
 .idea
 pubspec.lock
 .vscode/
+docs/doxygen/
+xcuserdata

ci/licenses_golden/tool_signature

-Signature: 72ebd2a03a8ef0d932f937c97ed540e5
+Signature: 4f2f6f3820bc3297f81495a994035ef4
 

docs/flutter-doxygen.css

+div.contents {
+    margin-bottom: 10px;
+    padding: 12px;
+    margin-left: 12px;
+    margin-right: auto;
+    max-width: 960px;
+}

tools/licenses/lib/main.dart

@@ -54,7 +54,7 @@ abstract class _RepositoryLicensedFile extends _RepositoryFile {
   // file names that we are confident won't be included in the final build product
   static final RegExp _readmeNamePattern = RegExp(r'\b_*(?:readme|contributing|patents)_*\b', caseSensitive: false);
   static final RegExp _buildTimePattern = RegExp(r'^(?!.*gen$)(?:CMakeLists\.txt|(?:pkgdata)?Makefile(?:\.inc)?(?:\.am|\.in|)|configure(?:\.ac|\.in)?|config\.(?:sub|guess)|.+\.m4|install-sh|.+\.sh|.+\.bat|.+\.pyc?|.+\.pl|icu-configure|.+\.gypi?|.*\.gni?|.+\.mk|.+\.cmake|.+\.gradle|.+\.yaml|pubspec\.lock|\.packages|vms_make\.com|pom\.xml|\.project|source\.properties)$', caseSensitive: false);
-  static final RegExp _docsPattern = RegExp(r'^(?:INSTALL|NEWS|OWNERS|AUTHORS|ChangeLog(?:\.rst|\.[0-9]+)?|.+\.txt|.+\.md|.+\.log|.+\.css|.+\.1|doxygen\.config|.+\.spec(?:\.in)?)$', caseSensitive: false);
+  static final RegExp _docsPattern = RegExp(r'^(?:INSTALL|NEWS|OWNERS|AUTHORS|ChangeLog(?:\.rst|\.[0-9]+)?|.+\.txt|.+\.md|.+\.log|.+\.css|.+\.1|doxygen\.config|Doxyfile|.+\.spec(?:\.in)?)$', caseSensitive: false);
   static final RegExp _devPattern = RegExp(r'^(?:codereview\.settings|.+\.~|.+\.~[0-9]+~|\.clang-format|\.gitattributes|\.landmines|\.DS_Store|\.travis\.yml|\.cirrus\.yml)$', caseSensitive: false);
   static final RegExp _testsPattern = RegExp(r'^(?:tj(?:bench|example)test\.(?:java\.)?in|example\.c)$', caseSensitive: false);