feat: add seller events and store the active sellers in Algolia

[ggarcia92]

Summary

This PR enhances the Seller module in MercurJS by adding new hooks, events, and subscribers that improve extensibility and synchronization with Algolia.

Proposed Changes

• Add a hook to the Seller Update workflow to allow greater customization during seller updates.
• Emit Seller Created and Seller Updated events whenever a seller entity is created or updated, enabling external integrations and automation.
• Add subscribers for the new Seller events to trigger corresponding Algolia update events automatically.
• Add subscribers for the Seller Algolia event to manage the list of active sellers in Algolia — adding active ones and removing inactive entries.

[ggarcia92]

I would love to contribute to your repository with this PR since I am working on a project that requires it, and it seems like a good improvement. Can someone provide a CONTRIBUTE guideline or a description on how this can be tested locally? I haven't found a description, and running the project with "yarn run mercur-dev" is not working, since the TS is telling that there are missing @mercurjs packages.

[LukaGiorgadze]

Same here, I opened a tiny PR #446 2 weeks ago, but no one is reviewing it, seems like the process is very slow...