[C++] lambda restrictions

Lambda Restrictions (as of c++26)

• No implicit conversions, e.g. base class slicing
• No member typedef
• No compiler-selected overloading
• No user-defined conversion functions
• No user-defined implicit copy/move operations
• No user-defined destructors
• Limited template argument deduction
• No directly extendable overload sets
• No operator overloading
• No array captures (at runtime. For compile time known size array, just like defined in struct, they are verbatimly copied/captured)
• No separating declaration and definition
• No linking across TUs (a lambda's type is effectively "private" to the file it is written in.)