Support simulating input data for test driven development through VSCode

[pcnfernando]

Integration use cases involve interacting with external systems, APIs, databases, and other services. Simulating these interactions can be challenging, especially when dealing with complex scenarios. A GUI-based simulation tool can offer several benefits rather than using tests.

For each data source, we want to simulate and implement the corresponding logic behind the GUI elements.

For example, if we are simulating an API endpoint, underneath implementation can be a ballerina test with a HTTP client that generates a request based on the provided constraints.

Appreciate your thoughts on this with regard to priority and feasibility.
@sameerajayasoma @hasithaa @gimantha

If we are to pursue this, we'll need to come up with a plan on what constructs we support simulating.