[C++] Move Directory method implementations from header to source file

[ryanvo504]

Describe the enhancement requested

Moves constructor, move constructor, move assignment operator, and member function implementations (Find, CreateEntry, AssignEntry, DeleteEntry) from inline definitions in the header to the source file. Also fixes duplicate "public:" access specifier in Entry class. This change improves compilation times and supports C++23 compatibility.

#47207

Component(s)

C++