Move all crates under crates/

Just organizational cleanup, a number of Rust projects
do this:
https://github.com/search?q=+%22crates%2F*%22+path%3ACargo.toml+-is%3Afork&type=code&p=5

Signed-off-by: Colin Walters <walters@verbum.org>

Cargo.toml

@@ -1,17 +1,5 @@
 [workspace]
-members = [
-    "cli",
-    "system-reinstall-bootc",
-    "lib",
-    "mount",
-    "ostree-ext",
-    "utils",
-    "blockdev",
-    "xtask",
-    "tests-integration",
-    "tmpfiles",
-    "sysusers",
-]
+members = ["crates/*"]
 resolver = "2"
 
 [profile.dev]