vpc: Remove Python dependency for embedding VScripts at compile-time

[copperpixel]

Description

This Python script is used as a custom build step to embed VScripts into the C++ code to run in the VScript VM.

It's a simple task that this PR ports to native scripting solutions (PowerShell and Bourne shell on Windows and Linux respectively) so it doesn't require installing a whole language interpreter.

[Generalisk]

I get errors while building on Windows

[copperpixel]

Replying to https://github.com/ValveSoftware/source-sdk-2013/pull/1664#issuecomment-3558440840

Can you show the build logs and does it still occur with the latest version?

[copperpixel]

~~Drafted for now since this can sometimes fail with multi-threaded building.~~