Reformat Swift code

[bernardnormier]

This is a small update to the Swift code formatting:

• change indentation size from 2 to 4 4 is the indentation size we use almost everywhere. It's also the indentation size in the Swift language guide: https://docs.swift.org/swift-book/documentation/the-swift-programming-language/controlflow

• increate the line length from 100 to 120 120 is what we use in C++, Objective-C++ C# and more

Note: in order to reformat your code, you need to run:

swift-format . --recursive -i --configuration .swift-format.json

from ice/swift.

[ReeceHumphreys]

Just for future reference, the .swift-format.json was generated by swift-format and contains just the default values prior to this PR EXCEPT AlwaysUseLowerCamelCase which we had to change due to our use of screaming case.