Return stub deployments when matching records do not exist.

[aronatkins]

The stub deployment is subsequently used to look-up the application by name. This lets showLogs, configureApp, setProperty, and unsetProperty interact with shinyapps.io when the client lacks a deployment record.

Does not address issues with publishing, such as #1013.

Fixes #985
Fixes #989

[toph-allen]

Checking my understanding: This works because the ShinyApps.io API works with just the info contained in the stub deployment.

[aronatkins]

Checking my understanding: This works because the ShinyApps.io API works with just the info contained in the stub deployment.

The getAppByName function only needs the server, account, and name to locate an application. That's enough to let these calls interact with shinyapps.io -- a full deployment record is unnecessary.

We likely need something similar for the re-deploy workflow, but that will probably need to create a full deployment record. The functions referenced in this PR were the only ones which used findDeployment(), which let me create a narrower solution.

[toph-allen]

Verification

Deployed a test app to ShinyApps.io and deleted the rsconnect subdirectory containing deployment records.

• On the previous version of rsconnect I'd see an error when running rsconnect::showProperties().
• On the version installed from GitHub containing this fix, I'm prompted to pick an account, and when I pick my ShinyApps.io account, I see the app's properties.