- prefer `null`, `!= null` and `== null` instead of `undefined`
- disallow `as`, add comments for the existing usages of `as`
- make `tsconfig.json` a bit stricter
- minor fixes to other files that were missed
# Important Notes
N/A
This PR replaces webpack with esbuild, as our bundler.
The change leads to out-of-the-box ~5x improvement in bundling times, reducing the latency in watch-based workflows.
Along with this a new development server (with live reload capacity) has been introduced to support watch command.
[ci no changelog needed]
### Important Notes
* workflow for checking docs has been removed because it was using outdated prettier version and caused troubles; while the same check is performed in a better way by the GUI/Lint job.
* introduced little more typescript in the scripts in place of js, usually with minimal changes.
