fix(core): In baseProvider, fixed autoselection of React stage

[alanmquach]

This doesn't feel great to me but it fixes things.

The problem was that when

1. There is only a single cloud provider configured for a stage that supports multiple
2. That stage is a React stage

We get an Invariant Violation: Target container is not a DOM element. because we try to immediately auto-select the only cloud provider, but the .react-stage-details div has not been mounted yet.

This defers the React render until after the digest cycle completes. Not great, but I think this can probably hold us over until we port the baseProvider code over to React (soon).

[ghost]

Yikes. Thanks for catching that.

[alanmquach]

@sbwsg Anytime. Does this need to be cherry-picked to the other releases?

[ghost]

Ah yes good call.

[ghost]

@spinnakerbot cherry-pick 1.12

[spinnakerbot]

Cherry pick failed: Command failed (cherry pick commit 7a49d82) with exit code 1:

error: could not apply 7a49d8222... fix(core): In baseProvider, fixed autoselection of React stage (#6673)
hint: after resolving the conflicts, mark the corrected paths
hint: with 'git add <paths>' or 'git rm <paths>'
hint: and commit the result with 'git commit'