Allow helper tools to be run via cargo run

Previously, only the `firecracker` binary could be run via cargo run.
Now, we can also do `cargo run --bin cpu-template-helper` for example. I
am keeping the jailer excluded from the `default-members` list, as this
seems to have been an intentional choice made in
3bf285c.

Signed-off-by: Patrick Roy <roypat@amazon.co.uk>

Author: roypat

Cargo.toml

@@ -1,6 +1,6 @@
 [workspace]
 members = ["src/clippy-tracing", "src/cpu-template-helper", "src/firecracker", "src/jailer", "src/log-instrument", "src/log-instrument-macros", "src/rebase-snap", "src/seccompiler", "src/snapshot-editor"]
-default-members = ["src/firecracker"]
+default-members = ["src/clippy-tracing", "src/cpu-template-helper", "src/firecracker", "src/rebase-snap", "src/seccompiler", "src/snapshot-editor"]
 resolver = "2"
 
 [profile.dev]