Shiny Express rsconnect issues

[gshotwell]

We discovered two issues with Shiny Express and rsconnect:

1. Currently it's really important that Express users upgrade their version of rsconnect-python but if they forget to do that they get kind of a weird error (the app deploys successfully and they get a runtime error when it starts up). It would be good if there were a check when a user was running their express app to see if the version of rsconnect-python were correct. So check if the user has rsconnect-python installed, and error if it's too old to deploy Express apps.

2. It doesn't look like rsconnect write-manifest shiny is detecting express apps. This is an important feature because it powers Connect git-backed deployment.

[gadenbuie]

Looks like there's an open and possibly related in rsconnect-python for the rsconnect write-manifest issue: posit-dev/rsconnect-python#540

[wch]

These have been fixed by #1233 and posit-dev/rsconnect-python#558.