Fix ScriptEditor inline colors float handling

[kitbdev]

• Fixes Inline color picker doesn't work well with non-constant colors #107725

Mostly whitespace changes since I tried to make the function easier to read.

split_floats just gives 0.0 when it encounters non-numbers, so I removed it and now check is_valid_float for each parameter, with a maximum of 4.
It must be a float literal, variables and expressions are not allowed here. It may be possible to use Expression to handle them, but it would still need to be readonly.

Also added checks when typing a string parameter to only show the color if it is valid and to prevent some invalid color errors (not all, see #89357).

This function will need to be moved to be language independent in the future, then it can be parsed better with GDScript.

[kitbdev]

Updated to show default color if the string isn't valid so it doesn't keep dissapearing and reappearing while typing.
Also now works with single quote strings. Though it will be changed to double quote when changing color.
Added more checks to prevent these cases being considered valid:

Color(")
Color("aaa)
Color(0xawaaaaaa)
Color(0x0 + aaaa)
Color("ff"+red)

There are still some colors that should be considered valid (like hex without alpha and more static methods) but those can be done later.

[KoBeWi]

Works fine now.
Needs rebase.

[Repiteo]

Thanks!