[maintainability] Cycles found in extension's code

After updating to a more recent version of `Eslint`, the linter started to report an issue with `ProgressMessages` in `vscode-trace-extension/src/trace-explorer/trace-tree.ts` having already been defined. After scratching my head for a while, I thought it could be a "cycle" issue. That turned-out to apparently be correct: see yellow lines in this graph, generated using "dependency-cruiser" \[1\]. The worst of it seems centered around `extension.ts`

Dependency graph (look at the yellow lines):


For info about the configuration I used and how to run `dependency-cruiser`, see this [commit on my fork](https://github.com/marcdumais-work/vscode-trace-extension/commit/e126c8751bbce622381f70a42ab69d5ca4bd1117)