--bin flag support?

[scullionw]

i have a crate that has two binaries in mycrate/src/bin/executable-a and mycrate/src/bin/executable-b

with cargo install i could cargo install --git XXX mycrate --bin executable-a

but the flag doesn't seem to exist with binstall, so we get failing installs with cargo binstall but not cargo install (since it requires both binaries but we only build one of the two binaries in our github releases)

ERROR resolve: When resolving gtfsrt-analyzer bin gtfsrt-analyzer-server is not found. This binary is not optional so it must be included in the archive, please contact with upstream to fix this issue.
 WARN resolve: Error while downloading and extracting from fetcher github.com: failed to find or install binaries: bin file /usr/local/bin/cargo-binstallQnXMs8/bin-gtfsrt-analyzer-aarch64-apple-darwin-GhCrateMeta/gtfsrt-analyzer-server not found

[NobodyXu]

Thank you for reporting!

I would welcome any PR for this