xtask: Add command for checking packages conform to certain standards (#15236)

This PR adds a new `xtask` command for checking that packages conform to
certain standards.

Still a work-in-progress, but right now it checks:

- If `[lints] workspace = true` is set
- If packages are using non-workspace dependencies

Release Notes:

- N/A

Cargo.lock

@@ -1906,6 +1906,15 @@ dependencies = [
  "wayland-client",
 ]
 
+[[package]]
+name = "camino"
+version = "1.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e0ec6b951b160caa93cc0c7b209e5a3bff7aae9062213451ac99493cd844c239"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "cap-fs-ext"
 version = "3.0.0"
@@ -1983,6 +1992,29 @@ dependencies = [
  "winx",
 ]
 
+[[package]]
+name = "cargo-platform"
+version = "0.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24b1f0365a6c6bb4020cd05806fd0d33c44d38046b8bd7f0e40814b9763cabfc"
+dependencies = [
+ "serde",
+]
+
+[[package]]
+name = "cargo_metadata"
+version = "0.18.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2d886547e41f740c616ae73108f6eb70afe6d940c7bc697cb30f13daec073037"
+dependencies = [
+ "camino",
+ "cargo-platform",
+ "semver",
+ "serde",
+ "serde_json",
+ "thiserror",
+]
+
 [[package]]
 name = "cargo_toml"
 version = "0.20.2"
@@ -9401,6 +9433,9 @@ name = "semver"
 version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b0293b4b29daaf487284529cc2f5675b8e57c61f70167ba415a463651fd6a918"
+dependencies = [
+ "serde",
+]
 
 [[package]]
 name = "serde"
@@ -13429,9 +13464,9 @@ name = "xtask"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "cargo_metadata",
  "cargo_toml",
  "clap",
- "toml 0.8.10",
 ]
 
 [[package]]