Relocate VGUI/script files for easy overriding #7292
Description
HUD customization for games can become a pain since it usually consisted of copying the default resource/script files and then modifying the entries or adding more directly.
For example, if you look at the hl2_complete/resource folder (whose search path was introduced since the 25 Anniversary Update, and takes priority), you'll find that sourceschemebase.res is empty, and instead, all the custom code is in sourcescheme.res, forcing customizations to copy this file initially when they could just start from an empty sourcescheme.res file and include the base one with #base sourceschemebase.res to inherit the default definitions.
The same could apply to other files, such as ChatScheme.res, ClientScheme.res and such, even when they never included a base file (which should be created to move the former files' contents as well).
This is a maintenance problem as you can see since users who modify their HUD have to merge their files with oficially updated content.