[docs] Bootstrap docs/landing page site

[bharatkashyap]

Deploy preview:

• https://deploy-preview-542--mui-toolpad-docs.netlify.app/toolpad/
• https://deploy-preview-542--mui-toolpad-docs.netlify.app/toolpad/getting-started/setup/

Partially fixes #477
Fixes #488

[render]

Your Render PR Server URL is https://toolpad-pr-542.onrender.com.

Follow its progress at https://dashboard.render.com/web/srv-cagvt9j19n0fr4mh1a10.

[render]

Your Render PR Server URL is https://toolpad-pr-542.onrender.com.

Follow its progress at https://dashboard.render.com/web/srv-cajp6350mal285rl1qig.

[Janpot]

@bharatkashyap Ok, this took some time to sort out. It's not finished, but at least there's something on the screen now.

The @mui/monorepo is a github dependency. yarn installs its dependencies so we can use things from e.g. the ./scripts folder. For the docs we are importing code from some of its workspaces. These are not installed in node_modules since yarn doesn't install workspaces of dependencies. Therefore anything trying to resolve them using the node module resolution algorithm (webpack) will fail to find them. Also their transitive dependencies are not installed. The workaround used in MUI X is to alias the package identifiers to their workspace inside the @ui/monorepo and by making sure that these packages are compiled.
I've removed the aliasing from babel config and added it to webpack. This really is a task for webpack, not for babel.
For this to work we must always make sure that:

• Any transitive dependencies for the monorepo are installed in the docs workspace (e.g. react or @emotion/styled)
• We specifiy the paths to the workspace packages correctly in next.config.json.

[Janpot]

@bharatkashyap Before we invest more time in the docs content, we need to sort out the FOUC. if it can't be solved, then I don't want to continue with this brittle setup.

[bharatkashyap]

Looks like @mui/toolpad-app is missing a dependency on @mui/utils?

Yes, this was the case. Fixed after adding this dependency to toolpad-app/package.json

[render]

Your Render PR Server URL is https://toolpad-pr-542.onrender.com.

Follow its progress at https://dashboard.render.com/web/srv-cb63dbcgqg45s1o6e7rg.

[Janpot]

Awesome!