feat(hyd): changed gear lever mechanism / added gear door drag

[crocket63]

Fixes #[issue_no]

Summary of Changes

Default gear lever mechanism using GEAR HANDLE POSITION simvar causes bugs with ground collision detection (landing gear down with gear lever up causes wheels going through the ground).

A custom lvar is added to handle the lever position only, and simvar GEAR HANDLE POSITION is built by system wasm depending on actual gear extension position

Added features:

• [x] Gear doors opened cause drag
• [ ] Gear lever animation shows it moving a bit when it's locked down

Screenshots (if necessary)

References

Additional context

Discord username (if different from GitHub):

Testing instructions

Check everything that can be affected by a massive gear system hack.

Non regression check non exhaustive list:

• Gear deployed still adds drag to the plane
• Systems using gear state and lever state are working properly (landing gear light...) ...

New features:

• Gear lever up. Gravity extension to get gear down with gear lever still up. Check plane lands normally and brakes correctly.
• Doors opened only (using gravity gear extension 2 turns only) adds some drag to the plane
• Collision detection works if you land with not all gears downlocked (use failures)
• Trying to pull gear lever up on ground shows the lever moving a bit up but refuses to go full up

How to download the PR for QA

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2. Click on the Checks tab on the PR
3. On the left side, click on the bottom PR tab
4. Click on the A32NX download link at the bottom of the page