Allow await on top level in Workspace

Currently, we cannot use `await` to wait for Promises in Workspaces (e.g. when `fetch`ing a resource).

To fix this: Update source code transformation to allow for top-level `await` statements.

When alternating the source code transformation, we have to consider the following:

- Arrange the order to move imports to the top of the file.
- Enclose all other statements in an asyncronous iife.
- the function should return a `do`-expression over all moved statements to provide the last evaluated statement as result
- take care of top-level variables, that still need to be recorded

Start by locating the Workspace source-code transformation entry point; the issue does not name a file or test. Trace how imports, top-level variables, and the final evaluated statement are currently handled before assessing the asynchronous IIFE and do-expression requirements. Done means Workspace code can use top-level await while imports remain first, variables are recorded, and the final statement remains the result.

Written by the indexing model from the issue text.