## Features

-  A `Toggle column` checkbox for adding / removing fields in the timeline offers
an alternative to drag and drop in an expanded event:

![toggle-field](https://user-images.githubusercontent.com/4459398/62572146-4d94c280-b850-11e9-8ff9-5feaca3f305d.gif)

The behavior of the `Toggle field` checkbox in the expanded event is the same
as the checkboxes that appear in the timeline _Fields Browser_.

## Fixes

- Pinned timeline events now use a "filled" styling when pinned instead of rotation, and unpinned events have a higher contrast in dark mode:

Before:

![unpinned-before](https://user-images.githubusercontent.com/4459398/62572175-5b4a4800-b850-11e9-9d4f-317d5abad002.png)

After (unpinned):
![after-unpinned](https://user-images.githubusercontent.com/4459398/62908225-28aebc80-bd34-11e9-9237-8a98c88a6da1.png)

After (pinned):
![after-pinned](https://user-images.githubusercontent.com/4459398/62908230-306e6100-bd34-11e9-9830-45d725bac5b1.png)

- Fixed an issue where the `Copy to Clipboard` icon rendered incorrectly (too
small, and not the right color):

Before:

![copy-to-clipboard-before](https://user-images.githubusercontent.com/4459398/62572224-7452f900-b850-11e9-962c-eef0b96202ff.png)

After:

![copy-to-clipboard-after](https://user-images.githubusercontent.com/4459398/62572240-7f0d8e00-b850-11e9-8b89-7c14bf92e705.png)

- Fixed an issue where a previously invisible control became visible and
occupied additonal row space in the timeline:

Before:

![row-height-before](https://user-images.githubusercontent.com/4459398/62572265-8e8cd700-b850-11e9-9c36-1d74ba0ba6f5.png)

After:

![row-height-after](https://user-images.githubusercontent.com/4459398/62572285-977da880-b850-11e9-8448-7085bbac8da4.png)

- Fixed an issue where the timeline Fields Browser Overlaps Column Headers

Before:

![field-browser-position-before](https://user-images.githubusercontent.com/4459398/62572309-a5332e00-b850-11e9-9b6f-38700d2f48a0.png)

After:

![field-browser-position-after](https://user-images.githubusercontent.com/4459398/62572335-b845fe00-b850-11e9-84f8-4b273f7ef163.png)

## Code Coverage and Cypress Tests

- This PR increases the `jest` unit test coverage for the _Fields Browser_, and
introduces `Cypress` tests for it
- Added new `Cypress` test helpers, configuration, and test refactorings to
support running smoke tests against remote Kibana instances, including
[Elastic Cloud](https://www.elastic.co/cloud)
- Refactored some `Cypress` tests to speed them up and reduce flakyness

elastic/siem-team#380
elastic/siem-team#431
elastic/siem-team#432
elastic/siem-team#433
elastic/siem-team#434
elastic/siem-team#435