fix: pushback did not pause when leaving flyPad Pushback page

[frankkopp]

Summary of Changes

When leaving the flyPad Pushback page while actually pushing back should set the pushback movement to pause.
This didn't work and this PR fixes this.

Also minor refactor to allow for better usage via LVARs in external tools.

Discord username (if different from GitHub): Cdr_Maverick#6475

Testing instructions

Test Pushback in general.
Test leaving the Pushback page while moving. Aircraft should stop.

How to download the PR for QA

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[Saschl]

LGTM

[marcman86]

Quality Assurance Report

Discord: marcman86#4907
Object of testing: #7645
Tier of Testing: 1
Date: 22/12/2022

Testing Process:

• Spawned at gate at EDDP
• Started up plane for taxi
• Turned on EFB
• Started pushback and checked all movements
• Left pushback page > movement stoped
• Go back to pushback page and resumed pushback
• Turned off EFB > movement stoped
• Turned on EFB again and resumed pushback
• Tested the same for controller inputs

Negatives: -

Testing Results: Passed
Conclusions: Works for me

Hope this helps :-)

[mico975]

Quality Assurance Tester Report

Discord : mico#3145
Object of testing: #7645
Tier of Testing : 1
Date : 25/12/2022

Testing Process:
Test Pushback in general. - OK
Test leaving the Pushback page while moving. Aircraft should stop. - OK

Negatives:
N/A

Testing Results:
Passed

Conclusions:
LGTM, maybe we can add a toggle for this feature in the future, because I somehow like to check other stuff on the EFB while pushing back with default to on.