Research: Delay-loaded DLLs for saner self-sandboxing

[MaulingMonkey]

Use cases:

• Have a single binary with both a UI component, and a low/untrusted launch token, without breaking user32.dll.
• rustc 1.63.0 std init with lower token?

References:

• Linker support for delay-loaded DLLs
• Understand the delay load helper function
• /DELAYLOAD (Delay Load Import)

[MaulingMonkey]

This is mostly a matter of using the right build.rs settings. This repository's build.rs contains an example.

Importing firehazard just for some lousy build.rs println!s seems a bit much / overkill. I could add a second crate for querying linker setting availability or something? But given the need for vaguely adjacent settings to be copy+pasted to live in .cargo/config.toml, that seems like overkill - examples should suffice, and I kinda have those already.