Enable updating a link with spin cloud link sqlite

[kate-goldenring]

Currently, to change the database linked to an app with a label, you have to unlink and then link.

$ spin cloud link sqlite --app boo-todo --database newname default
Error: Database "newdb" is already linked to app "boo-todo" with label "default"
$ spin cloud unlink sqlite --app boo-todo default
Database 'newdb' no longer linked to app boo-todo
$ spin cloud link sqlite --app boo-todo --database newname default
Database 'newname' is now linked to app 'boo-todo' with the label 'default'

With change, do not need to unlink to change a link.

$ spin cloud link sqlite --app boo-todo --database newname default
Database "newdb" is already linked to app "boo-todo" with label "default". Link to database "newname" instead? yes
Database "newname" is now linked to app "boo-todo" with the label "default"

[itowlson]

The request changes is for the prompt - the other comment is a flag for the future.

It's out of scope for this PR, but this reminded me that at some point we need to revisit this stuff to make it scripting/CI friendly. We've built the experience for interactive users but if someone runs it in CI then either it's going to block forever or the interactions will error out because no terminal (I am not sure if dialoguer checks for this case). Like I say, out of scope for this but something to ponder after 0.4 is out maybe.

[kate-goldenring]

We've built the experience for interactive users but if someone runs it in CI then either it's going to block forever or the interactions will error out because no terminal (I am not sure if dialoguer checks for this case). Like I say, out of scope for this but something to ponder after 0.4 is out maybe.

@itowlson I naively thought dialoguer's defaults handle this, but i see it does not based on our avoidance of it in spin https://github.com/kate-goldenring/spin/blob/0ed4c8234f16f525b642309ebe086dff4567ebcc/src/commands/plugins.rs#L483