Handle errors at Flink AI resource level

[Cerchie]

Summary of Changes

Fixes #3060

This PR handles errors at the Flink AI resources level, using Promise.allSettled to track the results of the resource loader and handle them accordingly. There's also a small helper method added to converts a promise rejection reason to an Error instance. 2 unit tests are added as well.

Clicktesting

1. run extension dev host and log into CCloud
2. Verify that no errors are thrown for empty Flink AI resoucers when they are loaded
3. Exit the ext dev host and modify the code to force an error:

    const [connections, tools, models, agents] = await Promise.allSettled([
      loader.getFlinkAIConnections(database, forceDeepRefresh),
      loader.getFlinkAITools(database, forceDeepRefresh),
      Promise.reject(new Error("Test error: Flink AI Models failed")),
      loader.getFlinkAIAgents(database, forceDeepRefresh),
    ]);

or something like this, if the nature of Promise.allSettled is not bubbling up what you want to verify (for me, it failed the other resources when I rejected one):

    if (connections.status === "fulfilled") {
      this.connections = connections.value;
//      resources.push(...this.connections);
//  } else {
      errors.push(["Flink AI Connections", this.toError(connections.reason)]);
    }

Then observe that the error is thrown and you see an appropriate notification.

Pull request checklist

Please check if your PR fulfills the following (if applicable):

Tests

• Added new
• Updated existing
• Deleted existing

Release notes

• Does anything in this PR need to be mentioned in the user-facing CHANGELOG?

[Copilot]

Pull request overview

This PR demonstrates two different error handling approaches for Flink AI resource loading: a TypeScript-style try/catch approach (commit 1) and a Go-style error handling approach with Promise.allSettled (commit 2). The implementation improves error resilience by allowing partial resource loading when some resource types fail, while providing clear error feedback to users.

Key changes:

• Replaced sequential await calls with concurrent Promise.allSettled for parallel resource loading
• Added graceful error handling that logs failures and shows user notifications while allowing successful resources to load
• Added comprehensive test coverage for error scenarios

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
src/viewProviders/multiViewDelegates/flinkAiDelegate.ts	Implemented Promise.allSettled-based error handling for Flink AI resource loading with user notifications
src/viewProviders/multiViewDelegates/flinkAiDelegate.test.ts	Added test coverage for error handling scenarios when resource loading fails

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.