[v1.12] Implement `progress` field in batch object

[curquiza]

Related to meilisearch/integration-guides#307

Explanation of the feature

• new progress field in the batch object

Usage: https://meilisearch.notion.site/Enhance-visibility-on-batched-tasks-1194b06b651f810b8fe0fab5d72846a8?pvs=74

TODO

👉 Check carefully the usage above to ensure your new methods and objects integrate all the functionnalities

• Ensure the batch object can accept the new field named progress. Check usage to get more detail
• Update current tests

⚠️ Make PRs pointing to bump-meilisearch-v1.12.0 and NOT main. Please do 1 PR for all of these changes, and not several.