Merge #4900

4900: Indexer edition 2024 r=Kerollmops a=dureuill

This PR is implementing the indexer edition 2024, largely inspired by [the ideas from this blog post](https://blog.kerollmops.com/meilisearch-is-too-slow).

Fixes https://github.com/meilisearch/meilisearch/issues/4985

## Features
- Stream-first approach to reading documents.
- Minimum disk write operations.
- RAM usage-first approach to avoid modifying common bitmaps on disk but in memory.
- Reduced LMDB fragmentation by writing entries only once...
- ...computing the final version of the entries in parallel...
- ...and storing them in write-optimized data structures before sending them to the BTree (LMDB).
- Indexing in multiple transactions to improve large dataset support (dumps).


Co-authored-by: ManyTheFish <many@meilisearch.com>
Co-authored-by: Clément Renault <clement@meilisearch.com>
Co-authored-by: Louis Dureuil <louis@meilisearch.com>

crates/index-scheduler/src/snapshots/lib.rs/import_vectors/Intel to kefir succeeds.snap

@@ -1,5 +1,5 @@
 ---
-source: crates/index-scheduler/src/lib.rs
+source: crates/crates/index-scheduler/src/lib.rs
 snapshot_kind: text
 ---
 ### Autobatching Enabled = true
@@ -23,7 +23,7 @@ succeeded [0,1,2,]
 doggos [0,1,2,]
 ----------------------------------------------------------------------
 ### Index Mapper:
-doggos: { number_of_documents: 1, field_distribution: {"_vectors": 1, "breed": 1, "doggo": 1, "id": 1} }
+doggos: { number_of_documents: 1, field_distribution: {"breed": 1, "doggo": 1, "id": 1} }
 
 ----------------------------------------------------------------------
 ### Canceled By:

crates/index-scheduler/src/snapshots/lib.rs/import_vectors/Intel to kefir.snap

@@ -1,5 +1,5 @@
 ---
-source: crates/index-scheduler/src/lib.rs
+source: crates/crates/index-scheduler/src/lib.rs
 snapshot_kind: text
 ---
 ### Autobatching Enabled = true
@@ -23,7 +23,7 @@ succeeded [0,1,]
 doggos [0,1,2,]
 ----------------------------------------------------------------------
 ### Index Mapper:
-doggos: { number_of_documents: 1, field_distribution: {"_vectors": 1, "breed": 1, "doggo": 1, "id": 1} }
+doggos: { number_of_documents: 1, field_distribution: {"breed": 1, "doggo": 1, "id": 1} }
 
 ----------------------------------------------------------------------
 ### Canceled By:

crates/index-scheduler/src/snapshots/lib.rs/import_vectors/adding Intel succeeds.snap

@@ -1,5 +1,5 @@
 ---
-source: crates/index-scheduler/src/lib.rs
+source: crates/crates/index-scheduler/src/lib.rs
 snapshot_kind: text
 ---
 ### Autobatching Enabled = true
@@ -22,7 +22,7 @@ succeeded [0,1,]
 doggos [0,1,]
 ----------------------------------------------------------------------
 ### Index Mapper:
-doggos: { number_of_documents: 1, field_distribution: {"_vectors": 1, "breed": 1, "doggo": 1, "id": 1} }
+doggos: { number_of_documents: 1, field_distribution: {"breed": 1, "doggo": 1, "id": 1} }
 
 ----------------------------------------------------------------------
 ### Canceled By: