Configure redirects for patterns and examples whose path change during repository restructure

[mcking65]

This issue is part of the Restructure repository Project.

As described in #2418, the paths of a few patterns and all examples will change when we land all the work described in that issue.

Following is the list of directory and file name changes that require redirects to be configured:

• The pattern directory name in the path for the modal dialog pattern is changing from /dialogmodal/ to /dialog-modal/. This affects the path of the pattern and all its examples.
• The pattern directory name in the path for the menu button pattern is changing from /menubutton/ to /menu-button/. This affects the path of the pattern and all its examples.
• All examples are moving from /wai/aria/apg/examples-index/PATTERN_DIRECTORY_NAME/EXAMPLE_NAME.html to /wai/aria/apg/patterns/PATTERN_DIRECTORY_NAME/examples/EXAMPLE_NAME.html. Exceptions to this pattern follow.
• The alert dialog example is moving from the modal dialog pattern to be under the alert dialog pattern, so the path is changing from: WAI/ARIA/apg/example-index/dialog-modal/alertdialog.html to WAI/ARIA/apg/patterns/alertdialog/examples/alertdialog.html
• The file name of the breadcrumb example is changing from "index.html" to "breadcrumb.html", so the path is changing from: WAI/ARIA/apg/example-index/breadcrumb/index.html to WAI/ARIA/apg/patterns/breadcrumb/examples/breadcrumb.html
• The multi-thumb slider example is moving from the slider pattern to be under the multithumb-slider pattern, so, the path is changing from: WAI/ARIA/apg/example-index/slider/slider-multithumb.html to WAI/ARIA/apg/patterns/slider-multithumb/examples/slider-multithumb.html
• The treeview-1 directory is removed from the path of the File Directory Treeview Example Using Computed Properties, so the path is changing from: WAI/ARIA/apg/example-index/treeview/treeview-1/treeview-1a.html to WAI/ARIA/apg/patterns/treeview/examples/treeview-1a.html
• The treeview-1 directory is removed from the path of the File Directory Treeview Example Using Declared Properties, so the path is changing from: WAI/ARIA/apg/example-index/treeview/treeview-1/treeview-1b.html to WAI/ARIA/apg/patterns/treeview/examples/treeview-1b.html

[mcking65]

see w3c/wai-aria-practices#172

[mcking65]

The content changes are live and redirects are tested and working.