Add missing tables to hasCustomAttribute and Implementation coded indexes and fix max column count comparsion according to spec

• hasCustomAttribute was missing MethodDef, DeclSecurity, GenericParam, GenericParamConstraint and MethodSpec tables in it's list, causing potential invalid index sizes
• Implementation was missing FileMD, causing potential invalid index sizes
• When calculating the index size, the maximum column count table was compared as "greater than" to max uint16. According to the spec, the index size should be 4 when they are equal aswell, so this should be fixed to greater or equal.

Spec references are attached.