feat: Login via CLI (#298)

Fixes #210 - this isPR implements `coder login` in the case where the default user is already created.

This change adds:
- A prompt in the case where there is not an initial user that opens the server URL + requests a session token
  - This ports over some code from v1 for the `openURL` and `isWSL` functions to support opening the browser
- A `/api/v2/api-keys` endpoint that can be `POST`'d to in order to request a new api key for a user
  - This route was inspired by the v1 functionality
- A `cli-auth` route + page that shows the generated api key
- Tests for the new code + storybook for the new UI

The `/cli-auth` route, like in v1, is very minimal:

<img width="624" alt="Screen Shot 2022-02-16 at 5 05 07 PM" src="https://user-images.githubusercontent.com/88213859/154384627-78ab9841-27bf-490f-9bbe-23f8173c9e97.png">

And the terminal UX looks like this:

![2022-02-16 17 13 29](https://user-images.githubusercontent.com/88213859/154385225-509c78d7-840c-4cab-8f1e-074fede8f97e.gif)

go.sum

@@ -1062,6 +1062,7 @@ github.com/pion/udp v0.1.1/go.mod h1:6AFo+CMdKQm7UiA0eUPA8/eVCTx8jBIITLZHc9DWX5M
 github.com/pion/webrtc/v3 v3.1.23 h1:suyNiF9o2/6SBsyWA1UweraUWYkaHCNJdt/16b61I5w=
 github.com/pion/webrtc/v3 v3.1.23/go.mod h1:L5S/oAhL0Fzt/rnftVQRrP80/j5jygY7XRZzWwFx6P4=
 github.com/pkg/browser v0.0.0-20210706143420-7d21f8c997e2/go.mod h1:HKlIX3XHQyzLZPlr7++PzdhaXEj94dEiJgZDTsxEqUI=
+github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8 h1:KoWmjvw+nsYOo29YJK9vDA65RGE3NrOnUtO7a+RF9HU=
 github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8/go.mod h1:HKlIX3XHQyzLZPlr7++PzdhaXEj94dEiJgZDTsxEqUI=
 github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=