Create local rust crate and update config path

In order to be able to run the CI on rust-vmm-ci we needed to
make it a rust crate. Also the path to the coverage config
file needed to be updated in test_coverage.py so that the path
does not depend on the crate; a breadth-first search was used
to guarantee that the config file belongs to the crate that is
being tested.

Signed-off-by: Catalin Dumitru <catdum@amazon.com>

src/lib.rs

@@ -0,0 +1,3 @@
+pub fn main() {
+    println!("It works!");
+}