Improve Icon loading on Canvas so the icons load in gracefully

[NickOpenFn]

Overview:

1. The icons on the canvas look great, however they are loading in and rendering very abruptly.
2. If there is any delay on the icons loading the text displays - which creates a strange experience of it loading "twice"

Possible Solutions:

• Add in a animation & wording to display on the nodes (this is good regardless of issue 2 above)
• Preload & cache the images to be ready to display when user logs in on the workflow overview page
• If preloading is not possible, then perhaps we improve the perceived display of these with animations. We delay the text by showing and then image from showing by .250ms, and then hopefully the images will be ready and display before the text.
• Another potential solution would be only to render the canvas once the images are ready.

[josephjclark]

I noticed this yesterday.

This is a fairly easy fix - what's happening is the app is downloading the icon manifest every time it renders an icon. For some reason it seems to be doing it serially too. Basically move the fetchAdaptorIconsData function in Job.tsx elsewhere and call it on mount.