storage: Right align idle message and spinner in the modal footers
storage: Right align idle message and spinner in the modal footers

Commit a0f826 adjusted the buttons in the modal footers to be left aligned but
missed the case of the storage dialogs where for the 'in progress'
operations the spinner and 'in progress' message has to be adjusted has
well.

Closes #13845
garrett/cockpit,garrett/cockpit,deryni/cockpit,deryni/cockpit,garrett/cockpit,mvollmer/cockpit,mvollmer/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,mvollmer/cockpit,garrett/cockpit,deryni/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,martinpitt/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,deryni/cockpit,cockpit-project/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,cockpit-project/cockpit,mvollmer/cockpit,deryni/cockpit,deryni/cockpit,cockpituous/cockpit,mvollmer/cockpit,martinpitt/cockpit,cockpit-project/cockpit,garrett/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,deryni/cockpit,cockpit-project/cockpit