Relax semver-checks to compare worlds in packages with different versions (bytecodealliance#1886)

In wasm-tools component semver-checks, instead of requiring that the old
and new world live in packages with the same id, just require that they
have the same name. This allows checking for semver compatibility
between different versions of a package, for example, this command:

```shell
$ wasm-tools component semver-check --prev wasi:http/[email protected] --new wasi:http/[email protected] ./wit
```

in a dirctory with `wit/deps/[email protected]` contains the current wasi-http
wit files, and `wit/deps/[email protected]` contains a new set of wit files,
checks that the new version is semver-compatible.

Author: sunfishcode

crates/wit-component/src/semver_check.rs

@@ -55,7 +55,7 @@ pub fn semver_check(mut resolve: Resolve, prev: WorldId, new: WorldId) -> Result
         .package
         .context("new world not in named package")?;
     let new_pkg_name = &resolve.packages[new_pkg_id].name;
-    if old_pkg_id != new_pkg_id {
+    if old_pkg_name != new_pkg_name {
         bail!("the old world is in package {old_pkg_name}, which is not the same as the new world, which is in package {new_pkg_name}", )
     }
 

tests/cli/semver-check-different-package-versions.wit

@@ -0,0 +1,14 @@
+// FAIL: component semver-check % --prev a:b/[email protected] --new a:b/[email protected]
+
+package foo:root;
+package a:b@0.2.0 {
+  world worldly {
+    import a: func();
+    import b: interface {}
+  }
+}
+
+package a:b@0.2.1 {
+  world worldly {
+  }
+}

tests/cli/semver-check-different-package-versions.wit.stderr

@@ -0,0 +1,5 @@
+error: new world is not semver-compatible with the previous world
+
+Caused by:
+    0: type mismatch for import `worldly`
+       missing import named `a` (at offset 0x186)