add support for multiplex signal parsing and syntax highlighting

[n0rbury]

Implements #4

Before:
Syntax highlighting for multiplex signals is buggy. Signals (and messages after that) don't show up in preview window.

After:

Attached is the sample dbc:

VERSION ""

NS_ :

BS_:

BU_:

BO_ 100 VehicleStatus: 8 Vector__XXX
  SG_ StatusCode M : 0|8@1+ (1,0) [0|255] "" ECU1
  SG_ Speed m0 : 8|16@1+ (0.1,0) [0|6553.5] "km/h" ECU1
  SG_ RPM m0 : 24|16@1+ (1,0) [0|65535] "rpm" ECU1
  SG_ Temperature m1 : 8|8@1+ (1,-40) [-40|215] "°C" ECU1
  SG_ Pressure m1 : 16|8@1+ (0.1,0) [0|25.5] "kPa" ECU1
  SG_ FuelLevel m2 : 8|8@1+ (0.5,0) [0|127.5] "L" ECU1

BO_ 200 SensorData: 8 Vector__XXX
  SG_ SensorID : 0|16@1+ (1,0) [0|65535] "" ECU2
  SG_ SensorValue : 16|32@1+ (0.001,0) [0|4294967.295] "V" ECU2

[lharri73]

1. 30k line change in one PR is crazy. I'm happy to entertain contributions, but it must be manageable. Feel free to break this up and I'll look at it.

2. I refuse to merge AI slop. I wouldn't care if it was a few lines or a new feature. But this is too much.

[n0rbury]

1. 30k line change in one PR is crazy. I'm happy to entertain contributions, but it must be manageable. Feel free to break this up and I'll look at it.
2. I refuse to merge AI slop. I wouldn't care if it was a few lines or a new feature. But this is too much.

Sorry, I just saw this after being tagged in the other topic. And sorry again for introducing unexpected commits in this PR, which was only supposed to contain the ef8a6e8. This is actually my first GitHub PR so I didn't really know how things work. That UI overhaul was added after me deciding to create a different extension based on yours and try something experimental with AI. It's completely understandable to refuse large AI commits like that (I would've done the same thing). I didn't even look into the UI/UX modifications myself because they were supposed to stay in my own fork only (and I can barely read typescript and javascript). To me AI just "magically" delivered what I expected...

I have created another PR with ef8a6e8 alone. Please check out that one. And I will keep bringing non-UI changes back to you if I can. Thanks again for making this super helpful extension :)