Make login to Deploy from deployctl easier

[willnewby]

What problem are you trying to solve?

I want an easier login flow for deployctl, instead of going to https://dash.deno.com/account#access-tokens, I'd like to stay on the command line.

Describe the solution you'd like

A CLI command: deployctl login which would pop open a link to dash.deno.com and authorize you, then transfer the token back down to my local machine, which saves it into a file which deployctl then references.

Describe alternatives you've considered

Not changing it, seems like a papercut in onboarding that we don't need.

Documentation, Adoption, Migration Strategy

New user onboarding could look like:

deno install -Arf https://deno.land/x/deploy/deployctl.ts
deployctl login
deployctl deploy --project=helloworld server.ts

Optionally, we could just kick off the login flow before the deploy flow if you're not already logged in, so you could just call:

deno install -Arf https://deno.land/x/deploy/deployctl.ts
deployctl deploy --project=helloworld server.ts

Which would install deployctl, login you into Deploy, and deploy your project in 2 lines.

Flow taken from:

[kwhinnery]

Dig it! Should also be able to create a project from the command line.