feat(types): add filter-input to HTMLElementTagNameMap

[nberlette]

This PR adds filter-input to the global HTMLElementTagNameMap interface.

This is essentially the type-level equivalent of adding the tag to the global registry.

Since it is now a globally-recognized element, it's treated as a first class citizen in
the DOM, receiving full type support when using <filter-input> directly in your code,
or adding event listeners, and so on.

Note: today I learned that renaming a branch after opening a PR immediately closes that PR. Sorry for the dupe 😞

[primer-css]

👋 Hello and thanks for pinging us! This issue or PR has been added to our inbox and a Design Infrastructure first responder will review it soon.

• 🎨 If this is a PR that includes a visual change, please make sure to add screenshots in the description or deploy this code to a lab machine with instructions for how to test.
• ⏩ If this is a PR that includes changes to an interaction, please include a video recording in the description.
• ⚠️ If this is urgent, please visit us in #primer on Slack and tag the first responders listed in the channel topic.