Improve Service Discovery Errors (AKA improve New API form)

[josemigallas]

What this PR does / why we need it:

• Improves the way "error scenarios" are managed in the form, such as when projects is an empty string or when there's any error code.
• Improves Flow typings
• Improves the UI flow by adding a loading spinner and disabling inputs when there's an ongoing request
• Simplifies some pieces of logic

Possible TODOs

• Find a better way to show loading state
• Improve the data structured received from the server
• Reduce amount of requests by checking for service discovery before selecting the radio
• Get projects/services data only once, not everytime the radio is selected (keep state in parent?)

Which issue(s) this PR fixes

THREESCALE-2646: Service Discovery: Improve error messages and visual feedback when ajax request fails

Verification steps

Having Service Discovery enabled and logged in in Openshift go to /apiconfig/services/new and select Import from Openshift. Mess around the form and look for any errors.

Visuals
Expected:

When empty:

When error:

[codecov]

Codecov Report

Merging #1015 into master will increase coverage by 0.2%.
The diff coverage is 33.33%.

@@            Coverage Diff            @@
##           master    #1015     +/-   ##
=========================================
+ Coverage   92.77%   92.97%   +0.2%     
=========================================
  Files        2403     2417     +14     
  Lines       78544    79561   +1017     
=========================================
+ Hits        72866    73974   +1108     
+ Misses       5678     5587     -91

Impacted Files	Coverage Δ
...n/service_discovery/cluster_projects_controller.rb	66.66% <0%> (ø)	⬆️
...n/service_discovery/cluster_services_controller.rb	50% <40%> (+7.14%)	⬆️
config/initializers/oracle.rb	1.49% <0%> (-44.78%)	⬇️
config/initializers/access_token_authentication.rb	55.55% <0%> (-22.23%)	⬇️
app/models/application_record.rb	62.5% <0%> (-18.75%)	⬇️
app/queries/new_accounts_query.rb	71.73% <0%> (-17.4%)	⬇️
lib/api_authentication/by_access_token.rb	91.52% <0%> (-5.94%)	⬇️
app/models/account/buyer_methods.rb	92.06% <0%> (-1.59%)	⬇️
app/lib/missing_model.rb	100% <0%> (ø)	⬆️
...est/workers/delete_object_hierarchy_worker_test.rb	100% <0%> (ø)	⬆️
... and 39 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 43383d8...c03f5d8. Read the comment docs.

[didierofrivia]

🏅