feat: mark memoized node as cached

[MenD32]

Fixes #13848

Motivation

when using memoization, its much easier to debug workflows when you can see that nodes have been cached. currently in large workflows you'd have to go over all the nodes one by one to understand if they are cached, or you could go to the timeline tab.
both of those options offer a bad user experience, that becomes worse as the workflows get larger.

Modifications

changed the icon of successful cached nodes to a database icon (from font awesome) to mark them as cached.

Verification

tested in the UI that it works using the examples/memoized-simple.yaml example

screenshots:

first workflow (no cache hit)

second workflow (cache hit)

[elliotgunton]

I like the choice of icon - for the abstract concept of "cached" it seems to align with the rest of the world https://www.google.com/search?q=icon+to+represent+cache

But replacing the check mark within the node itself might be confusing for existing and new users alike - it looks like it's a step related to database access, and two workflows running the same thing will look quite different. I would suggest an additive approach e.g. an overlaid database symbol - quick sketch from a google slide