Add alert for failed requests

[andchiind]

Closes #1008

[andchiind]

Ideally I would like the banner alert to be triggered in ApiCaller.tsx, so that it's integrated in the event handler. Then we could neatly decide how each request should be handled in a single file. This is difficult though since BackendAPICaller is a static class which does not have access to custom contexts, and so we therefore need to update the banner in .catch statements where the BackendAPICaller is used. It would be possible to implement this custom error handler in ApiCaller.tsx if we made the custom class into a custom context instead though.

[andchiind]

As a part of implementing the alert in such a way that the dialog closes itself when an error is returned, I ended up refactoring MissionQueueView.tsx and the dialog component file.

[Eddasol]

Gap between "Add mission" and "Create mission" changes when "Add mission" is pressed

[Eddasol]

Suggest updating style in "Request error" to match existing style for failed mission

[andchiind]

Suggest updating style in "Request error" to match existing style for failed mission

I've now made them as similar as possible without changing the information.

[andchiind]

Gap between "Add mission" and "Create mission" changes when "Add mission" is pressed

This should be fixed now.

[mrica-equinor]

LGTM :)