Sql keyword not quoted during serialization of query plan.

[Felicity-3786]

When a field has the name of Sql reserved keyword, trino fails to quote the word which results in JsonMappingException. For example, the sample query with the word "end" will fail:

CREATE TABLE base_table_test (a bigint, b row(c0 bigint, "end" bigint), c bigint);
INSERT INTO base_table_test values (5, row(6, 7), 8);

From the trace: Caused by: com.fasterxml.jackson.databind.JsonMappingException: line 1:34: mismatched input 'end'. Expecting: <identifier>, <type> (through reference chain: io.trino.server.TaskUpdateRequest["fragment"]->io.trino.sql.planner.PlanFragment["root"]->io.trino.sql.planner.plan.ProjectNode["assignments"]->io.trino.sql.planner.plan.Assignments["assignments"]->java.util.LinkedHashMap["b"])

[phd3]

Looks like the DataType serialization for RowDataType is missing quoting during serialization.

@Felicity-3786 would you like to pick this up to fix it?

[Felicity-3786]

Sure, will open a PR. Thanks!