Allows opening tests by default with share link

[satyarohith]

What kind of change does this PR introduce?
This PR helps us to have an option to set Tests view instead of Browser view when sharing sandboxes.

What is the current behavior?

What is the new behavior?

Checklist:

• Documentation
• Tests
• Ready to be merged
• Added myself to contributors table

closes #958

[satyarohith]

@CompuIves let me know whether this is useful since we can also achieve this from sandbox config files. :)

[CompuIves]

Yes! This is what we need! 😄

Could you also add the options to our docs? https://github.com/CompuIves/codesandbox-client/blob/master/packages/homepage/content/docs/2-embedding.md

[satyarohith]

Everything is done, Ives! 😃 Let me know if anything is missing.

[CompuIves]

This is almost done! The last thing we need to do is make it work in the embed, which can be done by setting the proper property here: https://github.com/CompuIves/codesandbox-client/blob/0fe309992d04fe0fc958c0125210893a90e53c73/packages/app/src/embed/components/Content/index.js#L436.

[satyarohith]

@CompuIves It works 🎉
Right now, preference is given to URL option if both config file and URL option are set.
Let me know what do you think? 😄

[CompuIves]

This is perfect @satyarohith, thanks a lot for the help! I'll let the build run now and merge it in as soon everything turns green. 😄🎉:shipit:

[kentcdodds]

Thanks!