feature: implement table sticky headers

[norbert-mieczkowski-codilime]

Implements: nautobot/nautobot-ui#39

What's Changed

Implement table sticky headers from nautobot-ui library. Apart from the obvious, the changes are following:

• List view layout components are now explicitly sized and they don't exceed the viewport size
• Skeleton loader slightly changed to better reflect the content being loaded
• Loader widget has inlined spinner and text
• The following React error with rendering invalid component is fixed:
  
• The tags are no longer getting excessive margins which made their containing table cells too large:
  

Loading	Table

[timizuoebideri1]

{!data_fetched && (
         <Box marginRight="md">
             <LoadingWidget name={tableTitle} />
         </Box>
   )}

I guess no need of the null

[norbert-mieczkowski-codilime]

It certainly is possible and well supported by React, though for safety and consistency the community prefers to use ternary operators anyway. Here's a blog post on that subject by Kent C. Dodds: https://kentcdodds.com/blog/use-ternaries-rather-than-and-and-in-jsx. I really recommend reading his blog as well as watching his talks, most of the time his thought process is brilliant.

[glennmatthews]

Interesting. This appears to work for me in Chrome but not in Firefox: