MiKo_1070 is now aware of 'document' types

[RalfKoban]

• Enhanced MiKo_1070_CollectionLocalVariableAnalyzer with new methods IsDocument and IsMefAggregateCatalog for better type checking.
• Updated ShallAnalyze method to exclude certain document types from analysis.
• Added comprehensive test cases to ensure no issues are reported for XML Linq nodes and custom document types.
• Refactored IsEnumerable method in SymbolExtensions to improve clarity and efficiency by using a local variable and additional braces.