feat: add support for script-based sort

[harshit98]

Summary of Changes

1. Introduced SortOption Interface:

• Added a new interface SortOption to enable different types of sorting options.
• Provided implementations for rawSortField and ScriptSortParams.

2. Script-Based Sort Implementation:

• Added ScriptSortParams to support script-based sorting, including its mapping to Elasticsearch-compatible formats.
• Provided a Map method to generate the required structure for script-based sorting.

3. New Sorting Methods in SearchRequest:

• Added methods like ClearSort, SortScript, SortRaw, and SortByScript to enhance flexibility in specifying sort criteria.
• These methods allow sorting by fields, scripts, or raw strings (e.g., _score).
• ClearSort will help us avoid accumulation and re-use of old sorting options from previous request.

4. Unit Tests for Script-Based Sorting:

• Extended the test cases with various scenarios of script-based sorting.
• Validated scenarios like sorting with scripts, sorting with raw fields, and combining multiple sorting criteria.

[harshit98]

Wrote a sample test case locally, looks like the current implementation is considering the old existing sort parameters from the old request. Let's discuss how we can solve this out.

=== RUN   TestSortReuse
    sort_test.go:187: Second request: expected {"sort":[{"field2":{"order":"desc"}}]}, got {"sort":[{"field1":{"order":"asc"}},{"field2":{"order":"desc"}}]}
    sort_test.go:217: Third request: expected {"sort":[{"_script":{"order":"asc","script":{"lang":"painless","source":"doc['field_name'].value"},"type":"number"}}]}, got {"sort":[{"field1":{"order":"asc"}},{"field2":{"order":"desc"}},{"_script":{"order":"asc","script":{"lang":"painless","source":"doc['field_name'].value"},"type":"number"}}]}
    sort_test.go:236: Fourth request: expected {"sort":[{"_score":{}}]}, got {"sort":[{"field1":{"order":"asc"}},{"field2":{"order":"desc"}},{"_script":{"order":"asc","script":{"lang":"painless","source":"doc['field_name'].value"},"type":"number"}},{"_score":{}}]}
--- FAIL: TestSortReuse (0.00s)