Make sharing link more discoverable

[floehopper]

This branch contains a couple of ideas I tried out to make the sharing link more discoverable as per this Trello card. The work isn't completely finished, but it would be useful to have feedback on whether any of the changes seem sensible...

• Initially only a maximum of 5 rows of the full results table in step 5 are displayed.

• A row displaying ellipsis is added to the table to indicate that other rows are missing.

• A "Display all rows?" checkbox is added at the top of that table. When checked all rows in the table are displayed.

• A "Copy to clipboard" primary button replaces the muted form text. Clicking the button copies the link to the clipboard and the button text changes to "Copied!" to give the user feedback.

TODO:

• The copy link button and its handler should probably be converted into a React component.

• The text of the copy link button should probably revert after a certain amount of time, so it's obvious you can click it again.

• If the data contains less than 5 rows, the ellipsis row should not be displayed.

[floehopper]

@spitschan You can preview these changes here.

[floehopper]

I've just pushed up changes to address the following:

TODO:

• The copy link button and its handler should probably be converted into a React component.

While I haven't actually turned the button into a React component - I've made the code a lot more React-y and I think it's fine for now.

• The text of the copy link button should probably revert after a certain amount of time, so it's obvious you can click it again.

The button text now reverts to "Copy to clipboard" after 1 second. Also while the text says "Copied!" the button is disabled.

[floehopper]

I've now pushed up a fix for the following:

TODO:

• If the data contains less than 5 rows, the ellipsis row should not be displayed.

I'm also not displaying the "Display all rows?" checkbox if there are less than 5 rows, because there aren't any more rows to display!

[floehopper]

I think this is all ready to merge from my point of view and @spitschan has already given it the go ahead here: https://trello.com/c/Az52kTKS/67-make-the-report-sharing-link-more-discoverable#comment-6012bd6f5df1a47cbe84bd6b. So I'm going to get it merged now.