Detects duplicate messages and channels aspects

This commit introduces extra checks to avoid duplicate aspects for messages and channels.
Closes #714

tests/unit/specification/parser_test.py

@@ -1924,76 +1924,6 @@ def test_parse_error_invalid_context_clause(tmp_path: Path) -> None:
     ):
         p.parse(test_file)
 
-def test_parse_error_duplicate_message_aspect_size() -> None:
-    assert_error_string(
-        """
-            package Test is
-                type M is
-                    message
-                        B : Opaque
-                            with First => 123, Size => 123, Size => 521;
-                    end message;
-            end Test;
-        """,
-        r'^<stdin>:6:61: parser: error: duplicate aspect "Size"',
-    )
-
-def test_parse_error_duplicate_message_aspect_first() -> None:
-    assert_error_string(
-        """
-            package Test is
-                type M is
-                    message
-                        B : Opaque
-                            with First => 123, Size => 123, First => 521;
-                    end message;
-            end Test;
-        """,
-        r'^<stdin>:6:61: parser: error: duplicate aspect "First"',
-    )
-
-def test_parse_error_duplicate_channel_aspect_readable() -> None:
-    assert_error_string(
-        """
-        package Test is
-
-            type M is
-                message
-                    B : Opaque
-                        with Size => 8;
-                end message;
-
-            generic
-                Channel : Channel with Readable, Writable, Readable;
-            session Session with
-                Initial => Start,
-                Final => Terminated
-            is
-                Message : M;
-            begin
-                state Start is
-                begin
-                    Channel'Read (Message);
-                transition
-                    goto Reply
-                        if Message'Valid
-                    goto Terminated
-                end Start;
-
-                state Reply is
-                begin
-                    Channel'Write (Message);
-                transition
-                    goto Terminated
-                end Reply;
-
-                state Terminated is null state;
-            end Session;
-
-        end Test;
-        """,
-        r'^<stdin>:11:60: parser: error: duplicate aspect "Readable"',
-    )
 
 def test_parse_error_duplicate_message_aspect_size() -> None:
     assert_error_string(