Support "Release, with symbols" mode

[mcclure]

I am using trunk to create wasm builds. I care a lot about the size of my emitted binary, so I am using the tool Twiggy to determine what functions/crates are contributing most to my binary size. A problem with Twiggy is it really needs symbol names to be useful. Without symbol names it can tell you that, say, a particular function is 16% of your binary size, but the function name is just a long hex number so this isn't actionable.

Trunk has previously added support for symbols in debug mode. However when testing for size debug mode becomes problematic. Debug/Release mode has an order-of-magnitude difference on file size (like, a 300k binary becomes a 2.6MB binary) and I worry that that size profiling on debug might be systematically misleading (for example what if a function is 16% of the binary in debug mode but only 2% with inlining from release mode or whatever).

Some buildsystems have an option where they build in release mode but with symbols included. Could Trunk add a version of this? (Building in release mode with symbols emitted as a separate file might also be as useful or more useful, but I don't know if this is possible in wasm or if twiggy would need changes to support it.)

[mcclure]

Wait, I'm sorry, trunk already has this capability and decides whether or not to include symbols based on the presence or absence of "strip=" in the Cargo.toml (the correct approach imo).