[WIP] Improve Gatsby starter

[AWolf81]

Related Issue:

47

Summary: After merging #335 I've noticed that entering an url or a starter name wasn't available. The Summary mentioned it but the functionality was removed because of the last UX improvement. Summary is correct again as the features are available once this PR is merged.

Added the following to the input field:

• Select starter by name e.g. enter gatsby-starter-blog
• Select stater by url e.g. https://github.com/gatsbyjs/gatsby-starter-blog
• Allow custom url with-out selecting a starter from the list e.g. https://github.com/2manyprojects2littletime/gatsby-starter-blog
• Test cases for the added functionality

Discussion

• Deleting the entered term in the input won't deselect the starter. I think that's OK - just wanted to mention it.
• Do we need an info that the url entered is valid? At the moment, there is no indication that it will be used. That's probably OK. We're only displaying a message if the starter wasn't found. I think that's a rare use-case we can improve later.
• Search improvement - @melanieseltzer mentioned it but I don't know it yet. But we can improve it with this PR.

[superhawk610]

I agree with @melanieseltzer, it shouldn't autoselect. If it's going to autoselect, there should be a more clear indication that the highlighted result is selected (something like the text SELECTED next to the result).

+1 for the No description text, I also think it looks better for consistency.

[AWolf81]

@melanieseltzer I've added a No description text for n/a entries so it looks consistent.

For the selection I've added a text to display that it will be selected. Styling is a bit basic and could probably be improved.

I think it's OK to autoselect as most user will probably just select a starter from the list and won't type it in the input box. They're typing it if they want to use a starter that's not listed in the starter list.