Constructron selection tool doesn't respect all `to_be_upgraded` entities

[wolfcomp]

Digging through the code and what is being returned I have found that not all entities to be upgraded has a item-request-proxy attached to it. This is being processed here https://github.com/ILLISIS/Constructron-Continued/blob/main/script/entity_processor.lua#L370-L372

Digging through the Factorio API there is a specific to_be_upgraded function that can be called for an entity to check if it is marked for an upgrade.

Things not checked for currently with this PR

• Does it use get_upgrade_target() to get the entity prototype out when checking what item to request for if its an entity to be upgraded
• Does it skip this step if Upgrade jobs is not selected