ref: Platform display

[cameronmcefee]

This updates the platform switcher behavior to be a little simpler on the user side.

The new platform selection priority is thus:

1. platform in the url
2. preferredPlatform in localStorage
3. DEFAULT_PLATFORM

The new general page load flow goes like this:

1. If platform is in the url, update preferredPlatform. If not, leave as is.
2. Update the UI based on preferredPlatform
   1. Update the dropdowns
   2. Update the url to show the preferred platform in case of copy/paste linking
   3. Show the proper platform content

Consequences:

• To provide a link to a document with a given platform displayed, set the url: sentry.io/mydocument?platform=erlang
• preferredPlatform is now set via the UI and/or the url value (previously url had no impact). This means following a link to a new platform sets that as your preferred platform until you navigate back to what you were on before

Removed:

• I'm no longer updating all links on the page with the current platform, because we're always checking preferredPlatform on page load and don't need to force the platform.

[mitsuhiko]

Approving based on the documented behavior. I think this generally makes sense and also should produce nicer looking URLs. 👍