Support aliasing metric names to handle refactors

[emschwartz]

The libraries should support adding an alias for the function and module names. When you add one or multiple aliases, it should produce metrics using the new name as well as the old name.

As @gagbo pointed out in autometrics-dev/autometrics-rs#66 (comment), we need to make sure that we don't double-count metrics when using them for SLOs.

• Rust
• Typescript
• Python
• Go

[emschwartz]

I'm going to close this for now but we can re-open it later when we plan to start working on it.