fix: accept optional colon in Spark STRUCT field specs

[cnbei]

Fixes sql-formatter-org#900

Spark SHOW CREATE TABLE emits STRUCT<field: type> (colon optional). The spark tokenizer had no : operator, so struct <c: bigint> failed with Parse error: Unexpected ": bigint> ".

Recognize : in the spark dialect and combine ARRAY<T> / MAP<K, V> / STRUCT<field: T> type tokens (same approach as BigQuery's parametric STRUCT, plus Spark's optional colon and MAP).

Tests

• Issue spark ddl with struct data type error sql-formatter-org/sql-formatter#900 CREATE TABLE DDL with struct <c: bigint>
• STRUCT fields without colon
• Nested ARRAY / MAP / STRUCT
• dataTypeCase: 'upper' on STRUCT field types

pnpm exec jest test/spark.test.ts — 278 passed.