Improving Triggering Hotkey functionality

[lorado]

Some summary outstanding points:

• I changed action name from "Trigger_Shortcut_By_Name" to "Trigger_Shortcut". It just makes more sense!
• New class Hotkey, which simply stores name, description and id of OBS Hotkey. UPDATE: instead of creating custom class and having stress with pointers, I decided simply to use existing obs_hotkey_t pointers. It works now without issues.
• There is also HotkeyModel, which is used as model on QComboBox in dropdown hotkeys list.
• In UI only description is shown, while name ist stored in the config. Config structure was not changed.
• I also changed hotkeys list filter - limiting only to hotkeys, which are registered with obs_hotkey_register_frontend() function, but hiding OBSBasic.* hotkeys. I also found a way to fetch the context name of the hotkey, source/scene, if any (like in the hotkey settings section). But they are currently filtered by type, because these hotkeys are registered with a different function, therefore it has a different type.

[lorado]

I updated code and made changes discussed on discord. Sorry, that I removed your QMaps, but using pointer in MidiHook is a better place in my opinion, to store hotkey related data, as they belongs directly to the hook. And it turned out, it works well with obs_hotkey_t directly

[lorado]

So, I did revert my functions using OBS hotkey instances, and used your code with QMap. This solution indeed needs a little bit less code.

[lorado]

most of the changes within this PR is actually clang-format output...