test all rust crates for realsies

After we merged legacy/trac#23881 (moved), it seems the tests in the tor_log crate aren't being run because there's an array in src/test/test_rust.sh that we didn't add the crate name to. I propose making that shell script automatically find the crates available and run their tests, e.g.

manifests=`find ${abs_top_srcdir:-.}/src/rust/ -mindepth 2 -maxdepth 2 -name 'Cargo.toml'`

(Currently, we're only running tests for crates="protover tor_util smartlist tor_allocate".)

As a side-note, I also think we should be calling cargo with --verbose so that our test logs actually tell us when something's wrong, e.g. for legacy/trac#24795 (moved) it would help.