fix(deps): bump jsforce from 2.0.0-beta.20 to 2.0.0-beta.21

[dependabot]

I (@mshanemc) hijacked dependabot's PR because of some test failures. This PR now

bumps the jsforce dep, and sfdx-core
modifies the bulk nut to be less verbose with polling status
makes bin/dev act like the CLIs with how they use oclif/fush. Say more?

sf/sfdx have this pattern, which is now applied to this plugin's bin/dev

.then(function (result) {
    require('@oclif/core/flush')();
  })
  .catch(function (err) {
    require('@oclif/core/handle')(err);
  });

it was previously doing

oclif.run().then(require('@oclif/core/flush')).catch(require('@oclif/core/handle'));

the NUT was failing because sometimes one last promise would return with data after the command returns. I can't say exactly why that happens with newer jsforce, but I think it's related to differences between beta 20 and 21.

Either way, it produces an error on the oclif/flush code because it isn't expecting to be passed a value, but with the late-resolving promise, it is. Then all kinds of problems happen.

This would be fine in the CLIs (where flush was handled like this plugin does now) but this messed the NUTs up pretty bad even when they were getting the correct json response.