fix(pretty-print): suppress child statement semicolons in CREATE SCHEMA

[edjubert]

What

CREATE SCHEMA takes a list of schema elements.
Per the grammar (OptSchemaEltList: OptSchemaEltList schema_stmt) they are space-separated and only the outer statement carries a terminator.
The emitter printed each child statement's own ;, producing invalid SQL:

-- input
CREATE SCHEMA s1 CREATE TABLE a (f1 int) CREATE TABLE b (f2 int);

-- before: does not parse
create schema s1 create table a (f1 int);create table b (f2 int);;

-- after
create schema s1 create table a (f1 int) create table b (f2 int);

Implementation

EventEmitter gains a no_semicolon flag that makes token() drop SEMICOLON; it is set while emitting schema_elts and cleared afterwards.
The separator before the element list becomes a soft line so the renderer can wrap when the schema name and the first element do not fit.

Tests

tests/create_schema_elts.rs round-trips a CREATE SCHEMA with two elements: format, reparse, normalize, compare ASTs.