[QLC5] VCPage: External keyboard controls are not reset corretly when unloading a project

[mauser]

Describe the bug

When loading a new project, the external keyboard controls of a virtual console's page (of the currently loaded project) are not emptied correctly. This may lead to situations where the external controls of a previously loaded project will be used for a different project (which has no external keyboard controls in its project file).

To Reproduce
Steps to reproduce the behavior:

1. Extract the attached zip , it contains two project files
   pageWithAndWithOutExternalControl.zip

   Project file "1page_withoutMapping.qxw" contains a virtual console page without any external control.
   Project file "1page_withKeyMapping.qxw" contains a virtual page with one external control ("Enable", by using Shift + X).

2. Load file "1page_withoutMapping.qxw", open virtual console.

3. Observe the "External controls" of the page "Page 1". The list is empty.

4. Load file "1page_withKeyMapping.qxw", open virtual console.

5. Observe the "External controls" of the page "Page 1". There is one external (keyboard) control: "Enable", by using Shift + X.

6. Load file "1page_withoutMapping.qxw" again.

7. Observe the "External controls" of the page "Page 1". The list should be empty (as in step 3), but it is filled with the event from Step 5:

Desktop (please complete the following information):

• OS: Linux
• QLC+ Version: 5, latest git version (79f9100)

[mauser]

Some observations from debugging: Unlike the related issue #2014, the cause does not seem to be the clearing of the members of the class VCPage. Those seem to be emptied correctly in VirtualConsole::resetContents().

But i discovered that the Class VCPage has a member m_keySequencesMap, as well its (indirect) base class VCWidget. While the VCPage::m_keySequencesMap is emptied by VirtualConsole::resetContents(), the input lists and mappings of VCWidget are still alive and filled. I am not familiar enough with the codebase to judge why this is and if it is intentional, but maybe this information is helpful for others with a deeper understanding of the code.