build: add release-lto profile for smaller binaries

[tharropoulos]

• add release-lto profile inheriting from release with fat LTO, single codegen unit, symbol stripping, and abort-on-panic
• keep default release profile lean with debug = 1 for backtraces during local development
• switch the release workflow to build with --profile release-lto so published binaries pick up the optimizations
• closes Enable Link-Time Optimization (LTO) and codegen-units = 1 for Release builds (and possibly other options) #28

[ploMP4]

The optimized settings should be on the release profile directly instead of a separate release-lto, since that's what cargo install uses from crates.io and anyone installing from there won't get a proper release build. I also don't think we need to account for local development here since we can just use the debug build for that anyway.

[tharropoulos]

I'm going off by what ripgreps already does.

[ploMP4]

I'm going off by what ripgreps already does.

Ripgrep does it this way, but they also document it in their README on the cargo install path:

If you're a Rust programmer, ripgrep can be installed with cargo.
...
Note that the binary may be bigger than expected because it contains debug symbols. This is intentional. To remove debug symbols and therefore reduce the file size, run strip on the binary.

Since cargo install is one of our main install methods I'm not sure this is the right call for us. What's the argument for keeping it this way over just putting the optimized settings on the release profile directly?