Fix the local database implementation of Client.batch()

[penberg]

We currently implement batch() by issuing every statement separately. Let's switch to libSQL batch interface instead (we need to expose it in libsql first).

[pihvi]

This might be related.. I'm initialising the DB on server start like this:

  const initSql = readFileSync(dir + '/init_sqlite.sql', 'utf8')
  const res = await client.execute(initSql)

The init file contains multiple satements like CREATE TABLE IF NOT EXISTS blabla..

This works locally, so when createClient gets url parameter with file:..., but when using Turso and giving url with libsql://turso... and authToken, it gives an error LibsqlError: SQL_MANY_STATEMENTS: SQL string contains more than one statement

Expected behaviour is consistency i.e. either both ways fail or succeed.