Serialize arrays in SQLite inserts, and return ids from batch inserts only when needed

[lehni]

What

A follow-up to #349, after a review of it:

• On SQLite, insert() stores objects and arrays in columns that aren't jsonAttributes as JSON in every insert, not only in batches. knex leaves arrays as '[object Object]' even in single rows, which Batch inserts on SQLite, and inserts of models with ids on all databases #349 didn't cover.
• SQLite batch inserts only add returning when there are ids to return. Models that have their ids aren't matched to the returned rows by position then, whose order SQLite doesn't guarantee.
• Batch inserts of models without an idColumn work on all databases, like models that have their ids, as there is nothing to return. Ids that $beforeInsert hooks give the models count too, and queries that a beforeInsert hook cancels don't throw.
• Docs:
  • SQLite needs 3.35 for batch inserts of new rows, and older versions fail with a syntax error near "returning".
  • In SQLite batch inserts, columns that some rows leave out get NULL instead of their defaults, as knex inserts them with select ... union all, and batches of more than 500 rows or 32766 values fail.
  • Many-to-many relate() of several ids works on all databases.
  • The changelog no longer says that graph inserts batch on SQLite, which only Rewrite upsertGraph() and insertGraph() (#1268, #1378, #1694, #853) #350 makes true.
• Tests:
  • These now run on every database:
    • many-to-many relate() of several ids
    • the $relatedQuery() array inserts, except on MySQL
    • the multi-model insert of Inserting into a table with no ID column gives Invalid column name 'id' Vincit/objection.js#2305
  • New SQLite tests cover JSON serialization, onConflict().ignore() in a batch, composite ids, and no returning for models with ids. Other tests cover ids from $beforeInsert hooks and cancelled batches on all databases.