Support alias foo = module std::io module aliasing.

test/test_suite/import/alias_attributes.c3

@@ -0,0 +1,3 @@
+module abc;
+
+alias test @if(true) = module abc; // #error: Module aliases cannot

test/test_suite/import/alias_bad_name.c3

@@ -0,0 +1,5 @@
+module foo;
+
+alias FOO = module abc; // #error: A (lower case) module name was expected here
+alias hellO = module abc; // #error: The module name must be all lower case
+alias hllo = module aBC; // #error: A module name may not have any

test/test_suite/import/alias_duplicate.c3

@@ -0,0 +1,7 @@
+module abc;
+import std;
+
+alias xyz1 = module std::io;
+alias xyz2 = module std::io;
+alias xyz3 = module std::io;
+alias xyz2 = module std::io; // #error: The module alias must be unique

test/test_suite/import/alias_no_match.c3

@@ -0,0 +1,3 @@
+module abc;
+
+alias test = module abg; // #error: No module named