fix for having a proper json schema for "where"

[durgesh-rathod-sf]

Description

Enhancement: Added proper support for where filter JSON schema in LoopBack to reflect all documented operators (e.g., eq, neq, gt, gte, inq, like, regexp, etc.) and logical clauses (and, or, not, nor), based on the [official LB4 filter documentation](https://loopback.io/doc/en/lb4/Where-filter.html#operators).

This improves the output of getWhereJsonSchemaFor() to generate accurate OpenAPI schemas and improves downstream schema validation/generation (e.g., for clients or Zod-based tools).

⚠️ Unit tests have not yet been updated or run in this commit. This PR is to get early feedback on logic and approach.

---

Checklist

• DCO (Developer Certificate of Origin) [signed in all commits](https://loopback.io/doc/en/contrib/code-contrib.html)
• npm test passes on your machine
• New tests added or existing tests modified to cover all changes
• Code conforms with the [style guide](http://loopback.io/doc/en/contrib/style-guide.html)
• API Documentation in code was updated
• Documentation in [/docs/site](../tree/master/docs/site) was updated
• Affected artifact templates in packages/cli were updated
• Affected example projects in examples/* were updated

---