feat(server): search unknown place (#10866)

* Allow submission of null country

* Update searchAssetBuilder to handle nulls

andWhere({country:null}) produces `"exifInfo"."country" = NULL`. We want
`"exifInfo"."country" IS NULL`, so we have to treat NULL as a special
case

* Allow null country in frontend

* Make the query code a bit more straightforward

* Remove unused brackets import

* Remove log message

* Don't change whitespace for no reason

* Fix prettier style issue

* Update search.dto.ts validators per @jrasm91's recommendation

* Update api types

* Combine null country and state into one guard clause

* chore: clean up

* chore: add e2e for null/empty city, state, country search

* refactor: server returns suggestion for null values

* chore: clean up

---------

Co-authored-by: Jason Rasmussen <jrasm91@gmail.com>
Co-authored-by: Alex Tran <alex.tran1502@gmail.com>
Co-authored-by: Jason Rasmussen <jason@rasm.me>

web/src/routes/(user)/search/[[photos=photos]]/[[assetId=id]]/+page.svelte

@@ -259,6 +259,8 @@
             {#await getPersonName(value) then personName}
               {personName}
             {/await}
+          {:else if value === null || value === ''}
+            {$t('unknown')}
           {:else}
             {value}
           {/if}