Allow to update all visors

[Senyoret1]

Did you run make format && make check?
The go code was not changed. npm run lint and npm run build were used.

Fixes #408

Changes:

• A button for updating all visors was added to the left bar in the visor list.

How to test this PR:
Use the button in the left bar in the visor list.

NOTE: the hipervisor API only returns an answer to the update request after finishing the procedure. This causes the hypervisor to return an error response if the internet connection is not fast enough to download everything before the timeout. Related issue: #413

[jdknives]

@Senyoret1 The button does not work for me. I can update the visor manually when clicking Update after accessing the visor, but there is no update found when using the Update all.

[Senyoret1]

@jdknives Thanks for noticing that, it should be working now. I also fixed a potential problem with offline visors.

[jdknives]

@Senyoret1 good job. The update mechanism works smoothly for the scenarios I tested.