[DSL] 7.1 Client integration

[margaretjgu]

Size: M

Description:
Integrate DSL packages with js client.

Implementation:

import { Client } from '@elastic/elasticsearch'
import { ESQL } from '@elastic/esql-dsl'

const client = new Client({ node: '...' })

// Query objects work directly
const query = ESQL.from('employees').where(E('salary').gt(50000))
const response = await client.esql.query({ query })

Acceptance:

• ES|QL queries accepted by client.esql.query()
• Search queries accepted by client.search()
• toString() called automatically where needed
• TypeScript types work with client
• Integration tests with real ES