Lack of progress updates when migrating volumes

##### ISSUE TYPE
* Improvement Request

##### COMPONENT NAME

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Volume operations
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##### CLOUDSTACK VERSION

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4.19.1.1
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##### CONFIGURATION

##### OS / ENVIRONMENT
Ubuntu KVM

##### SUMMARY

When migrating volumes between storages the qemu-img command does not report any progress anywhere, when moving large volumes it's useful to know how it is going.
It would be beneficial to add "-p" "convert" switch to qemu-img to get a progress then send the stdout/stderr to the agent.log or syslog.

##### STEPS TO REPRODUCE
Migrate a large volume between different various storages.
Takes a long time with no way to check (unless you start inspecting target volumes that is).

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##### EXPECTED RESULTS

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Command returns some progress to the user/operator, either in UI , logs, both etc.
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##### ACTUAL RESULTS

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No progress reports of any sort.
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Iniziate individuando il percorso di migrazione dei volumi che invoca qemu-img per Ubuntu KVM, quindi tracciate dove viene gestito l’output di agent.log o syslog. L’issue propone l’avanzamento di qemu-img convert e prevede che sia visibile agli operatori nei log, nella UI o in entrambi; confermate la posizione di output scelta durante la migrazione di un volume di grandi dimensioni.

Scritto dal modello di indicizzazione a partire dal testo della issue.