Show correct file sizes

[bspaans]

At the moment all files are listed with a size of 50000 bytes. This is a dirty hack and should be resolved. 0 size files broke a lot of tools on my mac unfortunately and I haven't found a way around that so the only thing I can think of at this point is to actually go and fetch the resources to calculate the size correctly.

This is a bit expensive because it has to run the kubectl behind the scenes for each file, but we can cache the results for a little while to alleviate this.