Instead of manually writing code to instantiate DOM elements in
MediaControls.cpp, use a Python script to generate a separate C++
struct to create and store the DOM elements.
The generator reads an HTML file and the HTML/SVG tags/attributes
headers to create C++ source that instantiates the DOM elements.
To enable embedding of stylesheets in shadow DOM, the generator
replaces `<link rel="stylesheet">` elements with plain `<style>`
elements containing the source from the linked stylesheet.
Elements that should be stored in the resulting struct should be marked
have the `data-name` attribute, which will be converted to snake_case
and used as the public field's name.
Optional elements can be marked with a 'data-option' attribute. Each
unique option value will be converted to PascalCase and added to a
bitwise enum named `Options` nested within the struct. Optional
elements and all their children will not be instantiated unless their
option is set in the constructor argument.
The MediaControls class stores the generated MediaControlsDOM struct
and sets up event handlers to implement user interactions.
