Integrate `gatsby-plugin-netlify-cache` for caching

[missmatsuko]

Feature request

In #193 (comment) it was discussed that the feature wouldn't be feasible until we could cache built assets. We were waiting for axe312ger/gatsby-plugin-netlify-cache#15 to be addressed, and it seems like that's happened. Maybe we can take a look to see if we can use gatsby-plugin-netlify-cache to cache?

What is the expected behavior?
Static/unchanged files should not be regenerated on every build.

What is motivation or use case for adding/changing the behavior?
Reduce build time, unblock #191 .

How should this be implemented in your opinion?
Using the plugin gatsby-plugin-netlify-cache.

Are you willing to work on this yourself?
Maybe, if it's not too complex.

[ZoltanVeres]

Hi @missmatsuko that's great news!
Can you add the gatsby-plugin-netlify-cache in the #193 PR?
I would configure the cache plugin to cache the public/icons folder for starters because that's where the gatsby-plugin-manifest is generating the icons
Once this is done you can recommit the icons, if needed, and perform the push.
Then we need a second push (could be text change) in which we could measure how much the buildtime si decreased.
Let me know if this sounds like a good plan or you need any help with this!