az spring-cloud app logs should support --deployment flag

### Extension name (the extension in question)
spring-cloud

### Description of issue (in as much detail as possible)

Currently, it is difficult to get logs from the staging slot of a spring cloud app. It would be great if `az spring-cloud app logs` could support a `--deployment` flag, similar to other app commands.

### Desired experience

Optional deployment setter:

`az spring-cloud app logs --deployment `

This would be a huge quality of life improvement. Because we use staging slots, when new deployments go awry, we are often debugging the staging slot deployment, instead of the production one.

I am happy to take a first stab at the work to enable this feature.

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