Refactor: Split node_3d_editor_plugin in multiple files

[quentinguidee]

I would like to make some improvements this week to the 3D viewport.

However, the node_3d_editor_plugin contains a lot of "unrelated" things, which led to 8780 lines, way too much to work properly.

This file containing 7 classes with an header of 950 lines, this PR split in 7 files, as advised in this issue: #33027 (comment) (3.).

Feel free to point out things to improve.

I have not edited any methods for this PR to simplify the review, except for the constants that I had to move to Node3DEditor.

[quentinguidee]

Does someone know why the CI static checks fail on this?

-/*************************************************************************/
+/*************************************************************************/

[Riteo]

@quentinguidee there's some weird junk at the beginning of the deleted line:

From `hexdump -Cv':

00000000  2d ef bb bf 2f 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |-.../***********|
00000010  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |****************|
00000020  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |****************|
00000030  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |****************|
00000040  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2f 0a  |**************/.|
00000050  2b 2f 2a 2a 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |+/**************|
00000060  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |****************|
00000070  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |****************|
00000080  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |****************|
00000090  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 2f              |***********/|
0000009c

I have no idea why the stuff marked as 2d ef bb bf is invisible, but it definitely confuses the hell out of my text editor.

Edit: 2d is actually -, so the troublesome part is just ef bb bf.

[Riteo]

Ok update: I used a fancy website and that's actually a single character: EF BB BF, also known as the infamous ZERO WIDTH NO-BREAK SPACE. I have no idea on how you added ZW spaces, but that's the culprit.

I should really learn to "decode" utf8 from hexdumps sometime.

[quentinguidee]

Thanks for your help! With this I found that JetBrains uses UTF-8 with what internet call "BOM" (UTF-8 BOM). I'll try to push the same code in 5min with UTF-8 classic to see if it fixes this.

Edit: let's see...

[Riteo]

Uh, the infamous BOM. Looking online, I found why it parsed as a ZWNBSP:

From https://en.wikipedia.org/wiki/Zero_width_no-break_space

The word joiner replaces the zero-width no-break space (ZWNBSP, U+FEFF), as a usage of the no-break space of zero width. Character U+FEFF is intended for use as a byte order mark (BOM) at the start of a file. However, if encountered elsewhere, it should, according to Unicode, be treated as a zero-width no-break space. The deliberate use of U+FEFF for this purpose is deprecated as of Unicode 3.2, with the word joiner strongly preferred.[1][2]

Damn you BOM!

Edit: yup, can confirm that it is indeed FEFF, I read the wrong column; that website also listed the plain binary UTF-8 data 😅

[quentinguidee]

Thanks! Static checks pass. Now let's face some fun compiling issues 😑

[quentinguidee]

Ok, Seems ready for review now.