Add feedback widget to docs sidebar

[scottybollinger]

Closes https://github.com/elastic/docsmobile/issues/697

This PR adds a feedback widget to the end of the right sidebar. This mimics the feedback experience that exists on https://docs.elastic.co.

Here is a video of the experience:

feedback.mp4

Notes:

• Because of the need for shared state but different locations in the markup (modal needs to be outside of the content and the widget in the sidebar), I opted to maintain all state in the modal component and use JavaScript to alter class names in the widget. The codebase contains redux, but I thought it overkill to wire up a solution that shares state as the need in the widget is minimal.

[glitteringkatie]

Wow it's been a while since I've seen react like this! Great job!

[elasticmachine]

💔 Build Failed

• Buildkite Build
• Commit: eadf49c

Failed CI Steps

• 🔨 Build docs PR

History

• 💚 Build #90 succeeded 4097c83

[scottybollinger]

💔 Build Failed

• Buildkite Build
• Commit: eadf49c

Failed CI Steps

• 🔨 Build docs PR

History

• 💚 Build #90 succeeded 4097c83

@nkammah can you tell me how to determine why this failed? Clicking on the link doesn't tell much and I've tried parsing the console output and nothing indiciates why there was a failure.

[nkammah]

@scottybollinger if you look all the way at the bottom of the build page, you'll see

Exited with status -1 (agent lost)

This means that the build agent ran out of resources (cpu/memory) and the build was interrupted.
I am trying to fine tune the values and speed up the build into another PR.

Note that this is the first time I see this type of failure on the docs repo :(

[nkammah]

Alternatively - it could be due to Buildkite having issues as posted to their status page: https://www.buildkitestatus.com/

[scottybollinger]

Thanks! 🙏