Merge #3505

3505: Csv delimiter r=irevoire a=irevoire

Fixes https://github.com/meilisearch/meilisearch/issues/3442
Closes https://github.com/meilisearch/meilisearch/pull/2803
Specified in https://github.com/meilisearch/specifications/pull/221

This PR is a reimplementation of https://github.com/meilisearch/meilisearch/pull/2803, on the new engine. Thanks for your idea and initial PR `@MixusMinimax;` sorry I couldn’t update/merge your PR. Way too many changes happened on the engine in the meantime.

**Attention to reviewer**; I had to update deserr to implement the support of deserializing `char`s

-------

It introduces four new error messages;
- Invalid value in parameter csvDelimiter: expected a string of one character, but found an empty string
- Invalid value in parameter csvDelimiter: expected a string of one character, but found the following string of 5 characters: doggo
- csv delimiter must be an ascii character. Found: 🍰 
- The Content-Type application/json does not support the use of a csv delimiter. The csv delimiter can only be used with the Content-Type text/csv.

And one error code;
- `invalid_index_csv_delimiter`

The `invalid_content_type` error code is now also used when we encounter the `csvDelimiter` query parameter with a non-csv content type.

Co-authored-by: Tamo <tamo@meilisearch.com>

meilisearch/tests/documents/add_documents.rs

@@ -216,6 +216,133 @@ async fn add_single_document_with_every_encoding() {
     }
 }
 
+#[actix_rt::test]
+async fn add_csv_document() {
+    let server = Server::new().await;
+    let index = server.index("pets");
+
+    let document = "#id,name,race
+0,jean,bernese mountain
+1,jorts,orange cat";
+
+    let (response, code) = index.raw_update_documents(document, Some("text/csv"), "").await;
+    snapshot!(code, @"202 Accepted");
+    snapshot!(json_string!(response, { ".enqueuedAt" => "[date]" }), @r###"
+    {
+      "taskUid": 0,
+      "indexUid": "pets",
+      "status": "enqueued",
+      "type": "documentAdditionOrUpdate",
+      "enqueuedAt": "[date]"
+    }
+    "###);
+    let response = index.wait_task(response["taskUid"].as_u64().unwrap()).await;
+    snapshot!(json_string!(response, { ".enqueuedAt" => "[date]", ".startedAt" => "[date]", ".finishedAt" => "[date]", ".duration" => "[duration]" }), @r###"
+    {
+      "uid": 0,
+      "indexUid": "pets",
+      "status": "succeeded",
+      "type": "documentAdditionOrUpdate",
+      "canceledBy": null,
+      "details": {
+        "receivedDocuments": 2,
+        "indexedDocuments": 2
+      },
+      "error": null,
+      "duration": "[duration]",
+      "enqueuedAt": "[date]",
+      "startedAt": "[date]",
+      "finishedAt": "[date]"
+    }
+    "###);
+
+    let (documents, code) = index.get_all_documents(GetAllDocumentsOptions::default()).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(documents), @r###"
+    {
+      "results": [
+        {
+          "#id": "0",
+          "name": "jean",
+          "race": "bernese mountain"
+        },
+        {
+          "#id": "1",
+          "name": "jorts",
+          "race": "orange cat"
+        }
+      ],
+      "offset": 0,
+      "limit": 20,
+      "total": 2
+    }
+    "###);
+}
+
+#[actix_rt::test]
+async fn add_csv_document_with_custom_delimiter() {
+    let server = Server::new().await;
+    let index = server.index("pets");
+
+    let document = "#id|name|race
+0|jean|bernese mountain
+1|jorts|orange cat";
+
+    let (response, code) =
+        index.raw_update_documents(document, Some("text/csv"), "?csvDelimiter=|").await;
+    snapshot!(code, @"202 Accepted");
+    snapshot!(json_string!(response, { ".enqueuedAt" => "[date]" }), @r###"
+    {
+      "taskUid": 0,
+      "indexUid": "pets",
+      "status": "enqueued",
+      "type": "documentAdditionOrUpdate",
+      "enqueuedAt": "[date]"
+    }
+    "###);
+    let response = index.wait_task(response["taskUid"].as_u64().unwrap()).await;
+    snapshot!(json_string!(response, { ".enqueuedAt" => "[date]", ".startedAt" => "[date]", ".finishedAt" => "[date]", ".duration" => "[duration]" }), @r###"
+    {
+      "uid": 0,
+      "indexUid": "pets",
+      "status": "succeeded",
+      "type": "documentAdditionOrUpdate",
+      "canceledBy": null,
+      "details": {
+        "receivedDocuments": 2,
+        "indexedDocuments": 2
+      },
+      "error": null,
+      "duration": "[duration]",
+      "enqueuedAt": "[date]",
+      "startedAt": "[date]",
+      "finishedAt": "[date]"
+    }
+    "###);
+
+    let (documents, code) = index.get_all_documents(GetAllDocumentsOptions::default()).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(documents), @r###"
+    {
+      "results": [
+        {
+          "#id": "0",
+          "name": "jean",
+          "race": "bernese mountain"
+        },
+        {
+          "#id": "1",
+          "name": "jorts",
+          "race": "orange cat"
+        }
+      ],
+      "offset": 0,
+      "limit": 20,
+      "total": 2
+    }
+    "###);
+}
+
 /// any other content-type is must be refused
 #[actix_rt::test]
 async fn error_add_documents_test_bad_content_types() {