Intent to prototype: autocorrect HTML attribute

[Makoto Kato]

Summary:
Software keyboard and some OS have auto correction features to
fix/replace a word and sentence while typing a character. Example,
macOS 10.6+ has a text substitution feature to replace with the
registered word when typing a word. This attribute and DOM property
can turn on/off this.

Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1725806
Specification: https://html.spec.whatwg.org/#autocorrection
Standards Body: WHATWG
Platform coverage: All. Android and macOS have backend implementations.
Preference: dom.forms.autocorrect
DevTools: Not needed
Other browsers:
Blink: Shipped HTML attribute only. No DOM property yet.
WebKit: Shipped without standard specification. But they had landed
https://bugs.webkit.org/show_bug.cgi?id=246344 for current
specifications.
web-platform-tests:
https://wpt.fyi/results/html/editing/editing-0/autocorrection