Add scroll to search request serialization.

[frivard-coveo]

Description

Add the scroll parameter when serializing the SearchRequest.

Issues Resolved

#676

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[reta]

@frivard-coveo could you please add an entry to CHANGELOG.md? thank you

[reta]

@VachaShah @dblock it seems like we don't have test cases for regular search functionality, I will add one shortly

[VachaShah]

@VachaShah @dblock it seems like we don't have test cases for regular search functionality, I will add one shortly

Thank you @reta! We have some search scenarios in samples as well: https://github.com/opensearch-project/opensearch-java/blob/main/samples/src/main/java/org/opensearch/client/samples/Search.java

[dblock]

This does need a test, let's add those as part of (merging) this PR.

[reta]

This does need a test, let's add those as part of (merging) this PR.

@dblock I've added basic Search API test (#678) so we could add more tests on top

[dblock]

This does need a test, let's add those as part of (merging) this PR.

@dblock I've added basic Search API test (#678) so we could add more tests on top

Thanks.

For this bug fix however we should make sure that there's a test that would fail without this fix.

[frivard-coveo]

Oh no!

I just realized that this PR is all wrong. The scroll parameter is supposed to be part of the query path, not the request body.
See this doc : https://opensearch.org/docs/latest/api-reference/search/#url-parameters
Unfortunately this means I'm back to square one trying to understand why my scroll requests are failing with "all shards failed".