Add JSON Schema Validation

[krishana7911]

Description:

Implement an optional feature to validate the JSON input against a user-provided JSON schema. This ensures the data meets expected structures before conversion.

Tasks:

• Add a --schema option to accept a JSON schema file.
• Validate the input JSON against the provided schema.
• Display user-friendly errors if the JSON doesn't match the schema.
• Ensure the table conversion only proceeds with valid data.

Example Usage:

json-to-table-cli --file data.json --schema schema.json --output table.md