Merge #4804

4804: Implements the experimental contains filter operator r=irevoire a=irevoire

# Pull Request
Related PRD: (private link) https://www.notion.so/meilisearch/Contains-Like-Filter-Operator-0d8ad53c6761466f913432eb1d843f1e
Public usage page: https://meilisearch.notion.site/Contains-filter-operator-usage-3e7421b0aacf45f48ab09abe259a1de6

## Related issue
Fixes https://github.com/meilisearch/meilisearch/issues/3613

## What does this PR do?
- Extract the contains operator from this PR: https://github.com/meilisearch/meilisearch/pull/3751
- Gate it behind a feature flag
- Add tests


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

meilisearch-types/src/features.rs

@@ -7,10 +7,12 @@ pub struct RuntimeTogglableFeatures {
     pub metrics: bool,
     pub logs_route: bool,
     pub edit_documents_by_function: bool,
+    pub contains_filter: bool,
 }
 
 #[derive(Default, Debug, Clone, Copy)]
 pub struct InstanceTogglableFeatures {
     pub metrics: bool,
     pub logs_route: bool,
+    pub contains_filter: bool,
 }