feat(tvix/store): init

Change-Id: Id846647fa456ff8b187ed4f16d035ce030f11d25
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7264
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
Reviewed-by: tazjin <tazjin@tvl.su>

tvix/store/src/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!("Hello, world!");
+}