WHOIS page: Add query variable for domain search input

[abroddrick]

Issue description

Now that we have the whois feature, when someone goes to get.gov/domains/choosing and enters a domain name, they could be accidentally entering it on the wrong page. For users who think they have a right to that domain name, they may also now be curious who has that domain and when did they get it.

In both these scenarios, it makes sense to show a link to the whois page on the availability error message (domains/choosing). This link should take them to the whois results page for that domain. For instance, searching for whitehouse.gov would get the error message mentioned in the AC and clicking the link will take you to the whois filled in.

Currently, get.gov does not support query variables so this ticket involves adding configurations for get.gov to support query variables and adding a query variable for a domain search input (/whois/?domain=lorem_ipsum.gov).

Acceptance criteria

• [ ] Configure 11ty settings to allow query variables. Possible leads in 11ty serverless page. You may also need to escape user input to counter malicious search queries.
• [ ] Add query variable for domain on the WHOIS page.
• [ ] On get.gov/domains/choosing, update the content to the unavailable error message so the link directs the user to a URL for the WHOIS search results of the searched domain: That domain isn’t available. [Learn about this domain.](link to WHOIS search results for that domain) <- see Figma

Additional context

No response

Links to other issues

• relates to #267

[h-m-f-t]

@katypies to create another sprint and move this to there. "Refined" by removing the refinement label.