Implicitly add the import when opening the form of a node template

[nipunayf]

Proposal

Currently, when opening a node form from the node palette, the imports required for the types used in the node are not automatically added to the source code. This results in unnecessary diagnostics about missing imports being displayed to users. This PR addresses this issue by automatically adding the required imports when opening a node form.

Approach

The implementation approach consists of four main components:

• Added importStatements to the central index property table, using comma separation for multiple imports since only _ is allowed in org/package/module names
• Implemented recursive processing for complex types (Unions, Tuples) to extract all required imports from member types
• Enhanced property codedata to include importStatements for consistent communication between extension and server
• Updated expression editor to automatically add both node-specific imports and dependent module imports (e.g., sql types for snowflake)

Security checks

• Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines? yes
• Ran FindSecurityBugs plugin and verified report? no
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets? no

[LakshanWeerasinghe]

how are we going to handle if user close the node template without saving anything?

[nipunayf]

how are we going to handle if user close the node template without saving anything?

When the user opens the form, the LS starts a shadowed project and applies all changes to that shadow project. If the user closes without saving, the shadowed project is closed, and the state reverts to what it was before opening the expression editor.