[FEATURE REQUEST] Add preprocessing symbol #if #endif on content's of generated code

[jeffcampbellmakesgames]

Is your feature request related to a problem? Please describe. A workflow was recently described on an easier way to refactor existing code that is also touched by auto-generated code. Rather than need to hand-modify auto-generated code where it had been changed, instead it was easier to:

• Surround the internal implementation of auto-generated code with a pre-processor symbol
• Set the preprocessor symbol when refactoring changes are needed (so that the internal implementation is compiled out)
• Refactor as needed and regenerate code.
• Unset the scripting symbol.

Describe the solution you'd like

• All internal implementations of auto-generated code should be surrounded with an #if !ENTITAS_REDUX_UNSET, #endif block.
• It would be helpful to have a menu item for setting/removing this as a scripting symbol in Unity so that a developer doesn't need to hand-modify the Scripting Symbols in the PlayerSettings.
• The implementation of auto-generated code should only be compiled out IF the scripting symbol is present.

[jeffcampbellmakesgames]

Menu Item for Toggling Refactor Mode I have a preview of this work available on branch feat/compile_out_implementation. A new menu item has been added such that a developer can execute it or press hotkey "Shift + Ctrl + R" to toggle a "Refactor Mode". When this mode is enabled, it will safely compile out all areas of auto-generated code's implementation related to component members and should make it easier for a developer to quickly refactor component members without needing to manually modify auto-generated code. When completed and before playing, this mode should be disabled.

Example code when refactor mode is enabled

[jeffcampbellmakesgames]

Merged to develop