fix(server): add filename search (#6394)

Fixes https://github.com/immich-app/immich/issues/5982.

There are basically three options:

1. Search `originalFileName` by dropping a file extension from the query
(if present). Lower fidelity but very easy - just a standard index &
equality.
2. Search `originalPath` by adding an index on `reverse(originalPath)`
and using `starts_with(reverse(query) + "/", reverse(originalPath)`. A
weird index & query but high fidelity.
3. Add a new generated column called `originalFileNameWithExtension` or
something. More storage, kinda jank.

TBH, I think (1) is good enough and easy to make better in the future.
For example, if I search "DSC_4242.jpg", I don't really think it matters
if "DSC_4242.mov" also shows up.

edit: There's a fourth approach that we discussed a bit in Discord and
decided we could switch to it in the future: using a GIN. The minor
issue is that Postgres doesn't tokenize paths in a useful (they're a
single token and it won't match against partial components). We can
solve that by tokenizing it ourselves. For example:

```
immich=# with vecs as (select to_tsvector('simple', array_to_string(string_to_array('upload/library/sushain/2015/2015-08-09/IMG_275.JPG', '/'), ' ')) as vec)  select * from vecs where vec @@ phraseto_tsquery('simple', array_to_string(string_to_array('library/sushain', '/'), ' '));
                                      vec
-------------------------------------------------------------------------------
 '-08':6 '-09':7 '2015':4,5 'img_275.jpg':8 'library':2 'sushain':3 'upload':1
(1 row)
```

The query is also tokenized with the 'split-by-slash-join-with-space'
strategy. This strategy results in `IMG_275.JPG`, `2015`, `sushain` and
`library/sushain` matching. But, `08` and `IMG_275` do not match. The
former is because the token is `-08` and the latter because the
`img_275.jpg` token is matched against exactly.

server/e2e/api/specs/search.e2e-spec.ts

@@ -212,4 +212,81 @@ describe(`${SearchController.name}`, () => {
       });
     });
   });
+
+  describe('GET /search (file name)', () => {
+    beforeEach(async () => {
+      const assetId = (await assetRepository.create(generateAsset(loginResponse.userId, libraries))).id;
+      await assetRepository.upsertExif({ assetId, ...searchStub.exif });
+
+      const assetWithMetadata = await assetRepository.getById(assetId, { exifInfo: true });
+      if (!assetWithMetadata) {
+        throw new Error('Asset not found');
+      }
+      asset1 = mapAsset(assetWithMetadata);
+    });
+
+    it('should return assets when searching by file name', async () => {
+      if (asset1?.originalFileName.length === 0) {
+        throw new Error('Asset 1 does not have an original file name');
+      }
+
+      const { status, body } = await request(server)
+        .get('/search')
+        .set('Authorization', `Bearer ${accessToken}`)
+        .query({ q: asset1.originalFileName });
+
+      expect(status).toBe(200);
+      expect(body).toMatchObject({
+        albums: {
+          total: 0,
+          count: 0,
+          items: [],
+          facets: [],
+        },
+        assets: {
+          total: 1,
+          count: 1,
+          items: [
+            {
+              id: asset1.id,
+              originalFileName: asset1.originalFileName,
+            },
+          ],
+          facets: [],
+        },
+      });
+    });
+
+    it('should return assets when searching by file name with extension', async () => {
+      if (asset1?.originalFileName.length === 0) {
+        throw new Error('Asset 1 does not have an original file name');
+      }
+
+      const { status, body } = await request(server)
+        .get('/search')
+        .set('Authorization', `Bearer ${accessToken}`)
+        .query({ q: asset1.originalFileName + '.jpg' });
+
+      expect(status).toBe(200);
+      expect(body).toMatchObject({
+        albums: {
+          total: 0,
+          count: 0,
+          items: [],
+          facets: [],
+        },
+        assets: {
+          total: 1,
+          count: 1,
+          items: [
+            {
+              id: asset1.id,
+              originalFileName: asset1.originalFileName,
+            },
+          ],
+          facets: [],
+        },
+      });
+    });
+  });
 });