SQLite FTS5 support

**Use case**

> Loading data from SQLite FTS5 tables directly into ClickHouse

**Describe the solution you'd like**

> Build SQLite with the FTS5 extension (and maybe the older FTS3/4 extensions too)

**Describe alternatives you've considered**

> Currently, I'm dumping data from FTS5 tables to CSV files (with the SQLite shell) and loading them into ClickHouse, which is slightly inconvenient!

**Additional context**

> None

The issue names no files, tests, or entry points. Start by locating ClickHouse's SQLite integration and build configuration, then determine how FTS5 tables should be exposed for loading; done means FTS5 data can be loaded directly without an intermediate CSV dump.

Written by the indexing model from the issue text.