[v1.10.0] Add CONTAINS operator

[brunoocasali]

Following this central issue

Explanation of the feature

Usage: https://github.com/orgs/meilisearch/discussions/763

New operator CONTAINS when using filter

TODO

• Add a new parameter to the dart DSL

[curquiza]

@brunoocasali, why this issue? It seems we pass string to "filter", and not something built, but I might be wrong:

meilisearch-dart/test/search_test.dart

Line 264 in 1d22b74

await index.search('prince', SearchQuery(filter: '"tag" = Tale'));

@ahmednfwela if you have the answer 😇

[ahmednfwela]

we have our own classes to map meilisearch operators, which are statically typed, and handle escaping
@curquiza

[ahmednfwela]

see here for example:

meilisearch-dart/test/search_test.dart

Line 657 in 1d22b74

await client.index('movie_ratings').search(

[curquiza]

Ok.... I have to say it seems very complicated for something we could have handled with strings only 🙈

[ahmednfwela]

well, the user can still use strings if they want, but having static typing for queries is definitely a good option

for example some users might mistakenly convert date time to iso string format, but we use epoch time