Make output set of $apply transformations available for subsequent transformations or other query operators

[ElizabethOkerio]

This PR fixes #945, #984

This fix makes this work:

http://localhost:5000/odata/Orders?$apply=groupby((Customer/Name), aggregate($count as OrderCount, TotalAmount with sum as Total))&$orderby=Total desc

Like you can use the output of $apply transformations, Total, in this case to perform subsequent transformations, $orderby in this case.

This is how the ApplyClause property looks like:

        public ApplyClause ApplyClause
        {
            get
            {
                if (_applyClause == null)
                {
                    _applyClause = _queryOptionParser.ParseApply();
                }

                return _applyClause;
            }
        }

So what happens when this is called: if (options.Apply?.ApplyClause != null). if ApplyClause is null,which will be null at this point, then the ParseApply gets called which parses the apply clause and binds the dynamic properties introduced in the $apply transformation. This makes these properties recognizable in subsequent transformations.

Before this change, the parsing of the apply clause was not happening before the $orderby gets called.

[gathogojr]

@ElizabethOkerio For my understanding, how did this regression come about and how does the seemingly innocuous code change fix the issue? Can you add an explanation in the pull request description?

[gathogojr]

[gathogojr]

@ElizabethOkerio Does this pull request fix this issue too? #984
If it does, please link it to this PR such that the issue will be closed when the pull request is merged.