fix: build errors on custom bin target names

[xJonathanLEI]

The current ELF-copying behaviour assumes that the built artifact is named the same as the crate itself. This may not be true when using custom project structures.

Usually, when explicitly using a custom structure, devs know that they need to use the --bin option (or the binary field, programmatically). However, sometimes this can happen implicitly. For example, moving src/main.rs to src/bin/hello.rs implicitly creates a bin target named hello. Since this happens without explicitly configuring Cargo.toml, devs may not know they need to use --bin. Also, since it works with the normal cargo build users may expect it also works with cargo prove build.

This PR fixes it by utilizing the target collection logic added in #1620 to accurately identify the full path to the generated ELF.

[github-actions]

SP1 Performance Test Results

Branch: jon/gro-162-non-standard-bin-target-name-fails-build
Commit: 341a1c82
Author: xJonathanLEI

program	cycles	execute (mHz)	core (kHZ)	compress (KHz)	time	success
fibonacci	11291	0.17	6.15	0.16	1m11s	✅
ssz-withdrawals	2757356	17.16	63.07	17.30	2m40s	✅
tendermint	12593597	6.33	165.89	63.94	3m19s	✅