Refactor/de-duplicate view XML and add a CDU close-up view

[ranguli]

(I was half-asleep when I originally made this PR.)

This PR adds a dedicated view option for the CDUs. I tried setting the view to the next unused number (105) but the view would not show up in FlightGear as an option unless I picked a different number. Additionally, I added this to common.xml as it wasn't immediately clear if it was necessary to also add it to common-IAE.xml (not sure what that is). If I need to add it in both places I can do that, or perhaps it would be better to add something like a views.xml file to contain the common views so there isn't as much duplication of code.

This PR adds the following:

• Currently, the views that are shared across all variants (Pilot, Co-Pilot, Engineer, Overhead, etc.) are defined twice, once in common.xml and once in common-IAE.xml. This PR moves these definitions into a new common-views.xml file. This provides the same functionality as before while de-duplicating the code, reducing complexity and improving organization.
• A new view has been added to common-views.xml, a close-up view of the CDU (all variants have the CDU, so it is 'common'). It also gives a good view of the radar beside it. The new view looks like this (note this screenshot is taken on an ultra-wide monitor, so it will vary slightly):
  

[NikolaiVChr]

Did you test this with all the variants? I think they have different views installed depending on the variant, did none of those break?
For example the awacs and joint stars has a radar officer view that the others don't have.

[ranguli]

I should not have made this PR while I was half asleep.. My apologies

Did you test this with all the variants? I think they have different views installed depending on the variant, did none of those break? For example the awacs and joint stars has a radar officer view that the others don't have.

It doesn't break any of the variants, but I did realize I need to push some changes to make the view work on all variants. (notably the ones with IAE engines in (common-IAE.xml)

Will push these changes later today

[ranguli]

@NikolaiVChr I've tested it and found that everything works as expected across all variants. It would be good for someone else to test it as well to confirm of course.