feat: add basic support for angular universal

[lindsaylevine]

This PR adds the minimum level support for an Angular Universal site like the site under /demo (aka the site from Jason's original proof of concept). Right now, it's missing some of the crucial monorepo logic that Matt built into the Next plugin. I think this can be excluded from a beta.

Callouts:

• @nguniversal/express-engine is installed at the top-level for CLI usage with the demo build because the plugin is looking at the top-level. I guess this is part of the missing monorepo work. Can this be changed with minimal adjustments, am I missing something, or should we invest in adding getAngularRoot logic akin to getNextRoot in the next plugin?

To-Do in a separate PR:

• ava test stuff
• update repo standards per luke's notion doc
• more graceful error handling for unmatched routes in builder func

[lindsaylevine]

according to tara:

we can always add later if needed

[tzmanics]

This is really great! Nice work!

I notice that in the readme we say to create a netlify.toml that has different information from demo/netlify.toml. Should they be the same?

[lindsaylevine]

This is really great! Nice work!

I notice that in the readme we say to create a netlify.toml that has different information from demo/netlify.toml. Should they be the same?

@tzmanics what different information are you referring to? the build command is the same, just in an npm script. the extra configs ([[redirects]] and [functions]) will be removed when the CLI pieces get fixed by workflow. is there somethin else?