Expand the CSC problem matcher to light up more errors on GitHub. (#717)

Expand csc problem matcher with more real-world scenarios.

Co-authored-by: Stephen Cleary <900597+StephenCleary@users.noreply.github.com>

.github/csc.json

@@ -4,13 +4,14 @@
             "owner": "csc",
             "pattern": [
                 {
-                    "regexp": "^([^\\s].*)\\((\\d+)(?:,\\d+|,\\d+,\\d+)?\\):\\s+(error|warning)\\s+([a-zA-Z]+(?<!MSB)\\d+):\\s*(.*?)\\s+\\[(.*?)\\]$",
+                    "regexp": "^\\s*(?:\\d+>\\s*)?([^\\s].*)\\((\\d+)(?:,(\\d+))?(?:,\\d+)*\\):\\s+(error|warning)\\s+([a-zA-Z]+(?<!MSB)\\d*):\\s*(.*?)\\s+\\[(.*?)\\]$",
                     "file": 1,
                     "line": 2,
-                    "severity": 3,
-                    "code": 4,
-                    "message": 5,
-                    "fromPath": 6
+                    "column": 3,
+                    "severity": 4,
+                    "code": 5,
+                    "message": 6,
+                    "fromPath": 7
                 }
             ]
         }