Improve the Microsoft.Data.Sqlite ADO.NET provider

[ajcvickers]

This is a grouping of related issues. Feel free to vote (👍) for this issue to indicate that this is an area that you think we should spend time on, but consider also voting for individual issues for things you consider especially important.

---

This an "epic" issue for the Microsoft.Data.Sqlite ADO.NET provider. Specific pieces of work will be tracked by linked issues.

Done in 6.0

• Microsoft.Data.Sqlite: Pool Connections #13837
• Sqlite: add transaction savepoint API #20228
• Microsoft.Data.Sqlite: Add Default Timeout connection string keyword #22505
• Microsoft.Data.Sqlite: Use Span overload of sqlite3_prepare_v2 #16202
• Microsoft.Data.Sqlite: Add Span overloads to SqliteBlob #16187

Done in 9.0

• Check commands[i] is not null for avoid NRE on Dispose command #22921

Backlog

• Microsoft.Data.Sqlite: Feature request: tracing, debugging #13832
• Microsoft.Data.Sqlite: Persist prepared statements across commands #14044
• Case-sensitive parameter names #18861
• Microsoft.Data.Sqlite: No SqliteDataAdapter #13838
• Microsoft.Data.Sqlite: Authorization Callbacks #13835
• Microsoft.Data.Sqlite: BackupDatabase() should yield #13834
• Microsoft.Data.Sqlite: Implement Data Change Notifications Callback #13827
• Microsoft.Data.Sqlite: Support System.Transactions #13825
• Microsoft.Data.Sqlite: Virtual table modules #13823
• Microsoft.Data.Sqlite: Add way to provide underlying SQLitePCL connection for SqliteConnection #21090

[roji]

Moved transaction savepoint API (#20228) up to proposed as there's a PR already out (#22869).