Add option to generate a default token on runner resource class creation [RT-6]

[christian-stephen]

Adds an option to the circleci runner resource-class create command to generate a resource-class token with the nickname default. This will help simplify the runner installation process.

[codecov]

Codecov Report

Merging #630 (d8243de) into master (ce8624c) will increase coverage by 0.36%.
The diff coverage is 60.00%.

@@            Coverage Diff             @@
##           master     #630      +/-   ##
==========================================
+ Coverage   27.06%   27.43%   +0.36%     
==========================================
  Files          40       40              
  Lines        4481     4490       +9     
==========================================
+ Hits         1213     1232      +19     
+ Misses       3119     3108      -11     
- Partials      149      150       +1     

Impacted Files	Coverage Δ
cmd/runner/instance.go	26.00% <0.00%> (ø)
cmd/runner/runner.go	75.00% <ø> (ø)
cmd/runner/token.go	55.00% <0.00%> (ø)
cmd/runner/resource_class.go	69.49% <80.00%> (+25.49%)	⬆️

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[pete-woods]

If people have scripted this command, it's going to be a breaking change.

It might make more sense to make it non-default, and have our install instructions include a --generate-token flag.

[christian-stephen]

If people have scripted this command, it's going to be a breaking change.

It might make more sense to make it non-default, and have our install instructions include a --generate-token flag.

Very valid point that also crossed my mind. I'll make the change and discuss with the team.