refactor(app): Allow app to request buildroot update token

[mcous]

overview

This PR is a chunk of implementation work for un-sized tickets #3359 and #3361. It implements the following steps in the migration + update process:

changelog

• refactor(app): Allow app to request buildroot update token

review requests

The diff is a little inflated because I had to split apart app/src/shell/buildroot.js as it was getting too large. Sorry about that.

A few decisions I made during implementation that will affect future work:

• App should only support updating one buildroot robot at a time
  • This can be changed in the future, but for MVP reduces scope of work
• HTTP requests/responses for buildroot update should live with the buildroot source, not the robot API client source
  • If bullet Error in Documentation #1 changes, this would likely change, too
  • For now keeps logic contained to one place
  • The update flow still uses actions from robotApi module, so really I mean the epics and reducer are in app/src/shell/buildroot rather than app/src/robot-api/resources/update-server or something

Things I'd especially like feedback on:

• Does the flow above actually work?
• This is my first time writing unit tests for epics, so (especially @b-cooper) if you have any insight here that would be great
• In the same vein, how do the epics in update-epics.js look?

real-life testing instructions

make -C app dev OT_APP_DEV_INTERNAL__ENABLE_BUILD_ROOT=1

Dispatch a buildroot:START_UPDATE action to a robot name, e.g.:

store.dispatch({type: 'buildroot:START_UPDATE', payload: 'opentrons-OT2P20180418A06'})

Pro-tip: Use the Chrome console rather than the Redux devtools to dispatch the action so you have up-arrow history as you're testing. Copy-paste in the app's devtools is very broken at least on macOS for some reason

Then, keep an eye on the Redux devtools for the following actions depending on which path in the flow you're following:

• buildroot:START_PREMIGRATION, buildroot:PREMIGRATION_STARTED, buildroot:PREMIGRATION_DONE
  • Robot was not ready for migration, so the update server was bootstrapped
• robotApi:START_UPDATE
  • Start update request will be re-dispatched after bootstrap is done and robot is migration capable
• robotApi:[REQUEST|RESPONSE|ERROR]__POST__/session/update[/migration]/begin
  • Token request, response, or error
  • Request path will change based on migration of BR update
• robotApi:[REQUEST|RESPONSE|ERROR]__POST__/session/update[/migration]/cancel
  • Token cancel request if initial token request came back 409
  • Request path will change based on migration of BR update

[codecov]

Codecov Report

Merging #3765 into edge will increase coverage by 0.14%.
The diff coverage is 98.68%.

@@            Coverage Diff             @@
##             edge    #3765      +/-   ##
==========================================
+ Coverage   57.09%   57.24%   +0.14%     
==========================================
  Files         817      820       +3     
  Lines       22545    22599      +54     
==========================================
+ Hits        12873    12936      +63     
+ Misses       9672     9663       -9

Impacted Files	Coverage Δ
app/src/pages/Robots/RobotSettings.js	0% <ø> (ø)	⬆️
app/src/discovery/selectors.js	84.9% <ø> (ø)	⬆️
app/src/robot-api/utils.js	62.85% <ø> (ø)	⬆️
app-shell/src/buildroot/index.js	0% <ø> (ø)	⬆️
...pp/src/components/RobotSettings/InformationCard.js	0% <ø> (ø)	⬆️
app/src/shell/buildroot/selectors.js	100% <100%> (ø)
app/src/shell/buildroot/actions.js	100% <100%> (ø)
app/src/shell/buildroot/update-epics.js	100% <100%> (ø)
app/src/shell/buildroot/reducer.js	92.3% <92.3%> (ø)
... and 3 more

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[sfoster1]

Tested as in the PR notes, works for me as long as the update server is from 3.7.0 or previous, or 3.10.1 or subsequent (in the middle the shape of the capabilities field in /server/update/health is wrong)

[b-cooper]

Tests look great! Awesome to have that epic coverage.

[b-cooper]

Sometimes I'll name the action parameter after a filter something that describes it's uniqueness if the flow type doesn't narrow it down enough (e.g. errorAction). Just a suggestion, though this is still pretty clear as is.

[mcous]

Will do so in #3771