Implement Subsetlist and covers_precise

[matteonu]

This PR adds new functionality to the Subset class

• Subsetlist is a new Subset that acts as a wrapper of existing subset types. It is essentially a list of Subset objects. The union of two Subsetlists is just the list concatenation.
• covers_precise() implements a set cover operation on Subsets of type Range and Indices. If it returns true the first input subset definitely covers the second input subset. Therefore it also takes steps into account.

[tbennun]

Thank you for the contribution. Before reviewing the PR, I have a minor naming comment: perhaps UnionSubset is a better name?

[matteonu]

Thank you for the contribution. Before reviewing the PR, I have a minor naming comment: perhaps UnionSubset is a better name?

I renamed it SubsetUnion now instead of UnionSubset (I switched the two words in my head somehow). I hope this works too. If not, I can change it again of course.

[matteonu]

Seems like subset_intersects_test.py fails in the build pipeline but I cannot reproduce it locally for some reason.

[tbennun]

It looks like DaCe is still installing SymPy 1.9, and that might be the reason: https://github.com/spcl/dace/actions/runs/6706005794/job/18223680540?pr=1412#step:4:521

Maybe try changing setup.py to reflect that (sympy >= 1.9)

[acalotoiu]

Thank you for the contribution! Please make it clear what all the tests are testing.

[matteonu]

Now the test should work.

[matteonu]

Now the test should work.
It seems like I forgot to set the sympy version back to 1.9 in the requirements.txt. I fixed it now.

[acalotoiu]

LGTM now! Thank you!