fix(clickhouse-driver): override generic string type in sqlTemplates

[AngelaMCarlos]

Description

Fixes #10415.

ClickHouse type names are case-sensitive: CAST(x, 'STRING') fails with Unknown data type family: STRING. Maybe you meant: ['String','Ring'].

ClickHouseQuery.sqlTemplates() overrides boolean and timestamp but not string, so any generated SQL that casts to the generic string type fails against ClickHouse:

• LAG/LEAD SQL API pushdown (since v1.6.14): internal columns are emitted as CAST(NULL, 'STRING') AS __user, CAST(NULL, 'STRING') AS __cubejoinfield (ClickHouse: CAST(NULL, 'STRING') fails — ClickHouseQuery missing string type override #10415).
• count measures over composite primary keys with the Tesseract planner (v1.7): the key concatenation is emitted as count(concat(CAST(pk1, 'STRING'), CAST(pk2, 'STRING'), ...)), so any such measure returns HTTP 400. Reproduced on v1.7.19 with a plain REST query on a cube whose dimensions declare two primary_key: true columns and a type: count measure without sql.

This one-line change adds templates.types.string = 'String'; next to the existing overrides, aligning the ClickHouse dialect with its case-sensitive type names.

Check List

• Tests has been run in packages where changes made if available — not run locally (one-line dialect override, submitted via web editor); happy to add a sqlTemplates assertion to clickhouse-query.test.ts if maintainers want one
• Linter has been run for changed code — change matches the surrounding style
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required — no doc impact