Add support for read-only mode in DuckDB and SQLite

[zaleslaw]

This commit introduces createConnection methods for DuckDb and Sqlite to handle read-only mode during connection creation. It also updates test configurations and ensures proper handling of in-memory databases.

Fixes #1365

[Copilot]

Pull Request Overview

This PR adds support for read-only database connections in DuckDB and SQLite by implementing database-specific connection creation logic. The main changes address the limitation where some databases require read-only mode to be configured during connection establishment rather than after.

• Implements createConnection methods for DuckDb and Sqlite to handle read-only mode appropriately
• Updates test configurations to use temporary files instead of in-memory databases for proper read-only testing
• Refactors connection handling logic to use database-specific connection creation

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
dataframe-jdbc/src/main/kotlin/org/jetbrains/kotlinx/dataframe/io/db/DbType.kt	Adds base createConnection method with default read-only handling
dataframe-jdbc/src/main/kotlin/org/jetbrains/kotlinx/dataframe/io/db/DuckDb.kt	Implements DuckDB-specific connection creation with read-only property support and in-memory database validation
dataframe-jdbc/src/main/kotlin/org/jetbrains/kotlinx/dataframe/io/db/Sqlite.kt	Implements SQLite-specific connection creation using reflection for SQLiteConfig
dataframe-jdbc/src/main/kotlin/org/jetbrains/kotlinx/dataframe/io/readJdbc.kt	Updates connection handling to use database-specific connection creation
dataframe-jdbc/src/test/kotlin/org/jetbrains/kotlinx/dataframe/io/sqliteTest.kt	Changes from in-memory to temporary file database for read-only testing
dataframe-jdbc/src/test/kotlin/org/jetbrains/kotlinx/dataframe/io/local/duckDbTest.kt	Updates read-only tests to handle in-memory database limitations
dataframe-jdbc/src/test/kotlin/org/jetbrains/kotlinx/dataframe/io/h2/h2Test.kt	Minor H2 connection string update

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[Copilot]

The connection properties (autoCommit) are being modified but not restored after use. Consider saving the original state and restoring it in the finally block to ensure proper cleanup in pooled connection environments.

Suggested change

	if (dbConfig.readOnly) {
	return connection.use { conn ->
	var originalAutoCommit: Boolean? = null
	try {
	if (dbConfig.readOnly) {
	originalAutoCommit = conn.autoCommit

[Jolanrensen]

Some small things only, good fix :)
(requires an apiDump call)