Convert offline update to use top progress bar instead of numerical value in snackbar

[srimanachanta]

Currently, when doing an offline update, the progress of the upload is displayed as a numerical percentage in the snackbar. Instead, a linear progress bar should be used at the top of the page.

https://v2.vuetifyjs.com/en/components/progress-linear/

[srimanachanta]

depends on #866