Develop 2.0 merge from cql to elm (and develop)

[baseTwo]

ℹ️Work for #371 and #386

Background

Prior to this PR, develop was merged into develop-2.0, and develop was merged into cql-to-elm.

This PR merges cql-to-elm and 'scopes' into develop-2.0. These branches deviated significantly over the past 4 or more months and merging them all back into one, is quite a challenge.

Remarks

• Updated the solution filter file Cql.slnf, to include the three new projects related to cql-to-elm
• Removed the folder Cql.Firely.Test, since it only had one unit test without any assertions
• The CqlOperatorBinder method binding logic had to be expanded. Previously only the inner generic argument was matched to the generic parameter, but now the argument itself is also tried. Meaning, previously when the input argument is CqlInterval and the parameter is T, then only CqlDate was tried on T. Now, CqlInterval is also tried.
• Added missing closing on CqlInterval operator
• ElmAsExpression must also take an argument for strictness
• Base test in CqlToElmTests must use LibraryExpressionBuilder instead of ExpressionBuilder
• The Lambda method was removed on ExpressionBuilder, but the CqlToElmTests still use it, so had to put an extension method for it there. Also, the ExpressionBuilderContext.TranslateArg method had to be opened from private to internal, to make this work
• The generated C# has many places where null is cast to a type. Must be fixed in issue #387 387.
• Always convert to result type when translating elements in ExpressionBuilderContext.TranslateElement. This is especially important when two arguments are passed to Equals, since it expects the argument types to be the same
• Fix ExpressionBuilderContext.ConceptRef by returning the type of the actual conceptRef, and not hard-coded CqlCode[] (#386)
• Small fix in CqlOperatorsBinder.
• Regenerate all C#

CMS Integration Tests

Running the integration tests (a separate repo from this) returns the following results:

• Tests passing before merge: 902 / 1822 (47%)
• Tests passing after merge: 1247 / 1822 (68%)

Questions

• Why is the length of a null string, null, but the length of a null list is zero? See tests LengthNullString and LengthNullList. The logic for Length can be found in CqlOperators.Length(string?) and CqlOperators.Length<T>(IEnumerable<T>?). I added the LengthNullString test in code and in the xml tests as well
• There are 2 XmlTests, one in CoreTests, the other in CqlToElmTests. The one in CoreTests is empty? My guess is the CqlToElmTests.XmlTests is replacing CoreTests.XmlTests and thus the latter must be removed?

[baseTwo]

Since this is a big merge between the three branches, @ewoutkramer suggested @EvanMachusak also reviewing

[EvanMachusakNCQA]

I removed the CoreTests version because the XmlTests in CqlToElm supplanted it.

[ewoutkramer]

All the warnings about new public API have to be resolved, otherwise it will not build....

[baseTwo]

The PR will be changed back to draft. The scopes branch will be merged as a separate PR, and the work before that will move over to another PR