Improve compatibility with legacy SQLite versions

[JanJakes]

SQLite Version Compatibility Fixes

This PR adds support for older SQLite versions by addressing various compatibility issues. It also updates the CI workflow to test against multiple SQLite versions.

Compatibility fixes:

1. UPSERT / ON CONFLICT clause (SQLite < 3.35.0) — The generic ON CONFLICT DO UPDATE clause without an explicit column list is only supported from SQLite 3.35.0. For older versions, we now catch the constraint violation error, parse the conflicting column names from the error message, and re-execute with an explicit column list.

2. STRICT tables (SQLite < 3.37.0) — The STRICT keyword for table creation is only supported from SQLite 3.37.0. It is now conditionally omitted on older versions.

3. VALUES list columnN naming (SQLite < 3.33.0) — Automatic column naming for VALUES lists (column1, column2, etc.) is only supported from SQLite 3.33.0. For older versions, we now emulate this by prepending a dummy SELECT NULL AS column1, ... WHERE FALSE UNION ALL ... header.

4. UPDATE ... FROM syntax (SQLite < 3.33.0) — The UPDATE ... FROM syntax is only supported from SQLite 3.33.0. We now avoid using it internally in the information schema builder.

5. IIF() function (all versions) — The IIF() function was added in SQLite 3.32.0. We now use CASE WHEN ... THEN ... ELSE ... END instead for broader compatibility.

6. SUBSTRING() function (all versions) — The SUBSTRING() function is not supported in older SQLite versions. We now translate it to SUBSTR().

7. sqlite_schema table (SQLite < 3.33.0) — The sqlite_schema table alias was added in SQLite 3.33.0. We now use the older sqlite_master name for compatibility.

8. SQLite version detection — Changed from using a SELECT SQLITE_VERSION() query to using the PDO::ATTR_SERVER_VERSION attribute for retrieving the SQLite version, which avoids extra queries by using SQLite C API directly.

9. CI workflow — Added support for testing against multiple SQLite versions.