Set up Prettier to enforce code style

[hoangphamEclipse]

Similar to the Trace Extension, we need to set up Prettier to enforce code style for the tsp-typescript-client. This includes:

[ ] Setting up Prettier in the repo so contributors can format their commits.
[ ] Setting up Prettier in CI to enforce code style.
[ ] Format the source code with Prettier.
[ ] Add documentation for Prettier.
[ ] Add a .git-blame-ignore-revs file to ignore the formatting commit.

Similar to this issue.