[dg cli] More clearly error if module name doesn't match what we expect (dagster-io#27662)

## Summary

Ran into this in the new `product-operations` purina code location,
which didn't have the same python module name as the code location name.
The error message gave me the runaround.


## Test Plan

New unit test.

Author: benpankow

python_modules/libraries/dagster-dg/dagster_dg/context.py

@@ -228,6 +228,10 @@ def components_path(self) -> Path:
         if not self.is_code_location:
             raise DgError("`components_path` is only available in a code location context")
         with ensure_loadable_path(self.root_path):
+            if not is_package_installed(self.root_package_name):
+                raise DgError(
+                    f"Could not find expected package `{self.root_package_name}` in the current environment. Components expects the package name to match the directory name of the code location."
+                )
             if not is_package_installed(self.components_package_name):
                 raise DgError(
                     f"Components package `{self.components_package_name}` is not installed in the current environment."
@@ -279,6 +283,10 @@ def components_lib_path(self) -> Path:
         if not self.is_component_library:
             raise DgError("`components_lib_path` is only available in a component library context")
         with ensure_loadable_path(self.root_path):
+            if not is_package_installed(self.root_package_name):
+                raise DgError(
+                    f"Could not find expected package `{self.root_package_name}` in the current environment. Components expects the package name to match the directory name of the code location."
+                )
             if not is_package_installed(self.components_lib_package_name):
                 raise DgError(
                     f"Components lib package `{self.components_lib_package_name}` is not installed in the current environment."

python_modules/libraries/dagster-dg/dagster_dg_tests/cli_tests/component_command_tests/test_component_commands.py

@@ -135,11 +135,27 @@ def test_component_scaffold_undefined_component_type_fails() -> None:
 
 def test_component_scaffold_outside_code_location_fails() -> None:
     with ProxyRunner.test() as runner, isolated_example_deployment_foo(runner):
-        result = runner.invoke("component", "scaffold", "bar.baz", "qux")
+        result = runner.invoke("component", "scaffold", "bar@baz", "qux")
         assert_runner_result(result, exit_0=False)
         assert "must be run inside a Dagster code location directory" in result.output
 
 
+def test_scaffold_component_command_with_non_matching_package_name():
+    with ProxyRunner.test() as runner, isolated_example_code_location_foo_bar(runner):
+        #  move the module from foo_bar to module_not_same_as_code_location
+        python_module = Path("foo_bar")
+        python_module.rename("module_not_same_as_code_location")
+
+        result = runner.invoke(
+            "component", "scaffold", "all_metadata_empty_asset@dagster_components.test", "qux"
+        )
+        assert_runner_result(result, exit_0=False)
+        assert (
+            "Could not find expected package `foo_bar` in the current environment. Components expects the package name to match the directory name of the code location."
+            in str(result.exception)
+        )
+
+
 def test_component_scaffold_with_no_dagster_components_fails() -> None:
     with ProxyRunner.test() as runner, isolated_example_code_location_foo_bar(runner):
         result = runner.invoke(