gdscript: allow color picking

[paul-marechal]

Implement DocumentColorProvider by extracting Color expressions, interpreting them, and replacing arguments in place when possible.

Add the following configurations:

• godotTools.colorPicker.precision: Controls how many decimals to include when applying edits.
• godotTools.colorPicker.padValues: Whether or not to pad decimal numbers.
• godotTools.colorPicker.uppercaseHex: Whether or not to write hexadecimals in uppercase when applying edits.

It should now be possible to get a preview of the color expressed by common Color methods, as well as pick and choose from a color palette provided by VS Code.

Only static expressions are evaluated, if you use a variable as one of the parameters then it will be ignored.

Color constant expressions are considered "readonly": The palette will show but provide no edits.

Test file:

Color.CYAN

Color()

Color("YELLOW")
Color("#ffff00")
Color("YELLOW", 0.5)
Color("#ffff00", 0.5)

Color(0, 1, 0)
Color(0, 1, 0, 0.5)
Color(0, 1, 0, 0.2)

Color8(255, 0, 0)
Color8(255, 0, 0, 128)
Color8(255, 0, 0, 0)

Color.from_rgba8(
    255, # red
            255, #green
    255,) #blue

Color.hex(
    0xFF00FFFF # best color
)

Illustration:

[paul-marechal]

Ideally this information should come from Godot itself through LSP?

I had a lot of pain trying to implement an ad-hoc way of parsing expressions to allow editing arguments in place as I felt like this was a desirable behavior (being a user of the extension myself)... But honestly the code required to allow for this is a bit much so I'd understand if we'd want to scrap it.

[DaelonSuzuka]

This looks good! I had starting building this feature last year but I got bogged down in supporting all the color formats and never finished it.

Give me a chance to play with this but I like what I see.

[paul-marechal]

Cleaned up a little and rebased on master.