Add the ability to review module upgrades

[mpchadwick]

Template updates / preferences / etc are also an issue when upgrading modules. We should also be able to use this tool to check for that.

[mpchadwick]

Spent some time reviewing what's required to implement

• Need documentation on creating diff. Probably something like this:
  • Create a backup of your project (cp -R . ../my-project-bak)
  • Upgrade the module
  • Create a diff of the backup of your project compared to your project with the upgrade
• Need to properly resolve file name in case of app/code module installs (https://github.com/sdinteractive/Magento2_SomethingDigital_UpgradeHelper/blob/5f492a4f345a1d4b7775b717b3ce72ab25a142d5/Console/UpgradeHelperCommand.php#L66)
• Need to be able to build list of preferences for module being upgraded (https://github.com/sdinteractive/Magento2_SomethingDigital_UpgradeHelper/blob/5f492a4f345a1d4b7775b717b3ce72ab25a142d5/Console/UpgradeHelperCommand.php#L51). Upgrade helper likely needs to accept a --module CLI option.
• Need to determine if we can resolve path to app/code preference via composer here (https://github.com/sdinteractive/Magento2_SomethingDigital_UpgradeHelper/blob/5f492a4f345a1d4b7775b717b3ce72ab25a142d5/Console/UpgradeHelperCommand.php#L53), probably not...
• May need to tweak here, although this may just work https://github.com/sdinteractive/Magento2_SomethingDigital_UpgradeHelper/blob/5f492a4f345a1d4b7775b717b3ce72ab25a142d5/Console/UpgradeHelperCommand.php#L89-L92