Misplaced/missing classification tests

[JHertz5]

Environment v3.27.0

Describe the bug The following classification tests inputs do not have a corresponding output and/or are in the wrong place, and are therefore not tested:

• ./tests/shared_variable_declaration/classification_test_input.vhd
• ./tests/interface_signal_declaration/classification_test_input.vhd
• ./tests/port_clause/classification_test_input.vhd
• ./tests/generic_clause/classification_test_input.vhd

Since these files are currently just dead code, we should either remove them or modify them so that they are tested. Doing the latter is more beneficial.

[JHertz5]

PR #1304 raised to address this issue.