C#: Add Line span pragma test case.

Author: michaelnebel

csharp/ql/test/library-tests/csharp10/linePragmas.expected

@@ -0,0 +1,5 @@
+linespan_directives
+| LinePragmas.cs:7:1:7:45 | #line ... | 1 | 1 | 1 | 30 | LinePragmasRef1.cs:0:0:0:0 | LinePragmasRef1.cs |
+| LinePragmas.cs:9:1:9:43 | #line ... | 2 | 1 | 5 | 32 | LinePragmasRef2.cs:0:0:0:0 | LinePragmasRef2.cs |
+linespan_offset
+| LinePragmas.cs:7:1:7:45 | #line ... | 5 | LinePragmasRef1.cs:0:0:0:0 | LinePragmasRef1.cs |

csharp/ql/test/library-tests/csharp10/linePragmas.ql

@@ -0,0 +1,13 @@
+import csharp
+
+query predicate linespan_directives(
+  SpanLineDirective directive, int startLine, int startColumn, int endLine, int endColumn, File file
+) {
+  file = directive.getReferencedFile() and
+  directive.span(startLine, startColumn, endLine, endColumn)
+}
+
+query predicate linespan_offset(SpanLineDirective directive, int offset, File file) {
+  file = directive.getReferencedFile() and
+  offset = directive.getOffset()
+}