Run delete_everything inside a transaction

[simonw]

This should use an explicit transaction to avoid "database locked" errors:

datasette/datasette/utils/internal_db.py

Lines 68 to 85 in b89cac3

	async def populate_schema_tables(internal_db, db):
	database_name = db.name
	def delete_everything(conn):
	conn.execute(
	"DELETE FROM catalog_tables WHERE database_name = ?", [database_name]
	)
	conn.execute(
	"DELETE FROM catalog_columns WHERE database_name = ?", [database_name]
	)
	conn.execute(
	"DELETE FROM catalog_foreign_keys WHERE database_name = ?", [database_name]
	)
	conn.execute(
	"DELETE FROM catalog_indexes WHERE database_name = ?", [database_name]
	)
	await internal_db.execute_write_fn(delete_everything)

[simonw]

This keeps on coming up with datasette.execute_write_fn() - I think it should automatically wrap a transaction around the function that gets executed.