Adds .prettierrc (default) because some prettier setups check its existence for formatting to work, and it is more convenient to have settings in a separate file.
Adds format:js command to package.json
Formats ts/js with prettier
Updates TypeScript version (because there were type errors in newly installed vscode-language deps during tsc compilation)
Adds tsc compilation task in .vscode/tasks.json (to run auto compilation while development)
format:js
command to package.json.vscode/tasks.json
(to run auto compilation while development)