Add pkginfo size output

[mhrono]

• Adds call to os.path.getsize() to get installer_item_size in bytes
• Adds output and description for installer_item_size

[mhrono]

@grahampugh as discussed in Slack last week, I've made the necessary changes to add size outputs to this processor and tested them successfully. This should be ready to go!

[grahampugh]

Curious as to why you removed installed_size?

[mhrono]

It was failing with a KeyError on a few test recipes and I couldn't figure out where it was having trouble getting the data. Happy to re-add it but I might need some guidance on troubleshooting the issue. The installer size has been working great.

[grahampugh]

To be clear, I don't require installed_size to be in there - I just wondered why the reason for removing. If it's not working and you don't need it, feel free to leave it out.

[mhrono]

Yeah, I'm trying to get it working again mainly to learn what I'm missing. I'll likely be making a few more commits to this branch as I poke at it and will let you know if/when it's working and ready.

[mhrono]

@grahampugh at long last, this is working and should be ready for review! I ended up breaking down each function and stepping through them to understand where the data was coming from and how it was flowing. Eventually I realized installerinfo was being checked for the installed size (which contains the output from getPkgRestartInfo) rather than receiptinfo, which actually contained the value.