Make workspace-loader (or UD) show an error received from websocket on workspace start failure

[garagatyi]

Description

When workspace start fails after some time workspace-loader and UD receive the message with the error, but provide UX that might be not clear to some users:

• There is a red circle near the workspace name
• There is no error shown
• The workspace loading progress bar doesn't disappear that might make a user think that workspace is still starting

Instead of that, it would be nice to:

• stop showing the progress bar
• show a popup with the error message and a button to restart the workspace (the same as reloading the page)

Reproduction Steps

OS and version:

Diagnostics:

[garagatyi]

@slemeur @ashumilova I decided to label this issue as a bug since it is about confusing UX when a user might not understand that workspace start failed and nothing will happen.
But feel free to relabel it as a task if you think otherwise.

[slemeur]

ok thanks @garagatyi