Add logging around CLI download fallback case

In CoderCLIManager, we have a fallback behavior to download the CLI to the data-dir. We should log something somewhere to let folks know that this is happening.

https://github.com/coder/jetbrains-coder/blob/5a4fb5950fbb561d0d79d11a0f45b4c8f9901147/src/main/kotlin/com/coder/gateway/cli/CoderCLIManager.kt#L78-L99

Open src/main/kotlin/com/coder/gateway/cli/CoderCLIManager.kt around lines 78-99 and trace the fallback path that downloads the CLI to the data directory. Add logging at the point where that fallback occurs, then verify that the fallback emits a useful message without changing its behavior.

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