Deduplicate stub game arena elements in tests

[Mikolaj]

Perhaps some values from UnitTestHelpers can be replaced by those in Game.LambdaHack.Common.Kind and surely some in other tests can be replaced by those in UnitTestHelpers, because in some cases they are identical.

If there is a benefit in the stub game arena elements being different in test files than in UnitTestHelpers, perhaps the extra ones should be moved to UnitTestHelpers, as well, and perhaps different blocks of tests in the same file could use different such elements, not just one.

[Mikolaj]

Example elements to deduplicate: testLevel, stubItem, testItemBase.

[kayvank]

@Mikolaj I would like to take this task plz.

[Mikolaj]

Good choice. I don't have comments at this point, but please feel free to ask questions at any time.

[kayvank]

@Mikolaj

testItemBase
is used in [test/ItemDescriptionUnitTests.hs(https://github.com/LambdaHack/LambdaHack/blob/master/test/ItemDescriptionUnitTests.hs#L23) only. Does it still need to be moved to UnitTestHelpers?

[Mikolaj]

Your call.

[kayvank]

I'll leave it there for now till we find a reuse for it down the line.
#292 is ready for your review please. than you for your help.

[Mikolaj]

My pleasure. PR's can be referenced as in #292 as well.

[Mikolaj]

Closed by #292.