Add IDL reflection tests for enumerated ARIA attributes

[rahimabdi]

Per: w3c/aria#2413.

ARIA will migrate a large set of attributes to be enumerated, so tests should be written for all the updated ARIA content attributes. This should be easily testable with an assert...() and ensuring that the tested ARIA IDL attribute reflects the content attribute, e.g.,:

assert_equals(el.ariaAttribute, el.getAttribute(ariaAttribute));

In addition to the missing value default and invalid value defaults, all keywords/states (including the canonical keyword) should be tested.

Misc considerations:

• Add a test for ensuring ariaInvalid reflection isn't impacted by setting validity IDL: [html-aam PR 395] add validity IDL w3c/aria#2223

Examples of existing WPT IDL tests

• <caption> IDL attribute (for <table>): https://github.com/web-platform-tests/wpt/blob/7bd6ffc4ff276671e5ea688631aaeb2b0bda0388/html/semantics/tabular-data/the-caption-element/caption_001.html#L51
• anchorElement IDL attribute: https://github.com/web-platform-tests/wpt/blob/3f8c984dcb82c8694d4c32432f885d39b7bef7b0/html/semantics/popovers/popover-anchor-idl-property.tentative.html#L18