Adds bracket matching validation to parser

Adds validation to ensure that brackets and braces are properly matched in the format parser.

This prevents incorrect parsing when there are mismatched brackets/braces.

Author: niemyjski

tests/Exceptionless.DateTimeExtensions.Tests/FormatParsers/TwoPartFormatParserTests.cs

@@ -48,7 +48,7 @@ public static IEnumerable<object[]> Inputs
                 ["blah",             null, null],
                 ["[invalid",         null, null],
                 ["invalid}",         null, null],
-                
+
                 // Mismatched bracket validation
                 ["{2012 TO 2013]",   null, null], // Opening brace with closing bracket
                 ["[2012 TO 2013}",   null, null], // Opening bracket with closing brace