## Description:
https://github.com/openfrontio/OpenFrontIO/issues/776
I've implemented upgradable structures for cities and ports.
As of right now this is just meant as a QOL change for structure
stacking that currently happens and no gameplay changes are intended.
Structure upgrades cost the same as making a new structure of that type
and function the same as making a new structure of that type.
I'm putting up a draft PR for this now since adding support for SAMs and
Silos will take more time to handle the cooldowns and I want to make
sure I'm on the right track for getting this merged.
I also still need to add bot behavior for this and re-enable min
distance for structures.
I didn't see translations for the UnitInfoModal so I've left that out
for now.
I've tested locally in a single player game so far but will document and
test more thoroughly before merging.


## Please complete the following:
- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors
## Please put your Discord username so you can be contacted if a bug or
regression is found:
# Poutine
---------
Co-authored-by: Scott Anderson <scottanderson@users.noreply.github.com>