Support Queries (prepared, execute all, etc.)

[asg017]

In order to properly support shadow tables or more advanced SQLite extensions, sqlite-loadable will need to expose some SQLite C APIs like sqlite3_prepare_v2() + sqlite3_step() + sqlite3_column_*(). That way, extensions can call CREATE TABLE xyz_foo() or INSERT INTO xyz_foo or SELECT * FROM xyz_foo for shadow tables or other more advanced usecases.

This will unblock a few features/extensions:

• sqlite-ml
• parquet_storage vtab in sqlite-parquet
• xsv_store in sqlite-xsv?
• sqlite-docs

Planned API features:

• Statement struct that prepares a sqlite3_stmt
  • create (sqlite3_prepare_v2)
  • bind parameters (sqlite3_bind_*())
  • iterate through results (sqlite3_step) (sqlite3_column_*())
  • Wrap sqlite3_mprintf() in rust for easier/safer string escaping, for shadow table creations